Simple Monster Variation

The adventures are heading into the troll city, and you'd like to make sure the encounters stay interesting without making dozens of custom stat blocks.  If your PCs are facing the same sort of enemy for an extended time, you may be looking for a way to spice things up.

Making the monsters a little different isn't a challenge on its own, but we want something that's quick and simple to set up, and doesn't slow things down when running the game.  Luckily, there is a way:

1d6	Boon	Bane
1	Heavy armor: +4 AC	Light armor: -4 AC
2	Fast: +10' move	Slow: -10' move
3	Tough: +50% HP	Weak: -50% HP
4	Fortunate (physical): Advantage on Strength/Dexterity/Constitution Saving Throws	Unfortunate (physical): Disadvantage on Strength/Dexterity/Constitution Saving Throws
5	Fortunate (mental): Advantage on Intelligence/Wisdom/Charisma Saving Throws	Unfortunate (mental): Disadvantage on Intelligence/Wisdom/Charisma Saving Throws
6	Talented: Advantage on attribute checks	Untalented: Disadvantage on attribute checks

For each creature you want some variation of, roll twice on the table, once for the boon, once for the bane.  If you get the same number on both rolls, the creature is just normal, and has neither effect.  All you need to note for each creature is what you rolled as long as you have the table handy.

Not every Boon and Bane on creature will cancel-out to be perfectly balanced, but in larger and multiple groups, they will average out.  A single tough and slow creature will effectively have a higher CR, but as the party face many creatures with different variations, it shouldn't be a worry.

A nice side-effect is that the Boon/Bane combinations is they can give the creatures some roles/tactics in the group.  Talented creatures might opt for grappling/shoving, weak creatures prefer staying at range, etc.

Feel free to customize the table to fit the creatures and the PCs -- at low levels the HP and AC modifiers might need to be a little smaller, or you might want to switch or add a modifier for size/reach variation if that makes sense for the creatures in question, etc.

Swords and Sorcerery (but all about the Sorcerery)

One of the trickiest things (in my opinion, at least) that D&D tries to balance is the relative power of magic vs. martial classes.  Magic is meant to be impressive, powerful, and swing the tides of battle.  But if the wizards and sorcerers can cast their biggest spells all day long, all the time, then what glory is left for the fighters and rogues and their other martial friends?

(the following is a bit of a train-of-thought working through some mechanics and balance, feel free to skip down to the class table

To preserve balance, there have been different approaches:  Magic users "forgetting" their spells after casting them, slower leveling progression, etc.  Warlocks can use many of their spells without limitation, though they are of lower power than wizard or sorcerer of equal level could cast.

But most magic users of fiction, be they like Gandalf, or Harry Potter, or from somewhere else, rarely work that way.  They can use magic (within their knowledge) almost without limit.  Some fictions might have magic that has a fleeting drain or exhaustion that becomes apparent as the caster reaches their limit, but usually that's about it.  Can we do the same thing in D&D?

Psionic classes in the current and past few versions of D&D (and some sorcerer variants) have used power points as a replacement for spell slots, which gives some additional versatility, but generally has relied on a once-per-day or long rest reset.  If power points refreshed more quickly, can we get some semblance of balance?

Let's start with the spell's cost.  If we make cantrips cost 1 power point (pp), then we can let everything else costs 2pp for each level of the spell (so a 3rd-level fireball would be 6pp).  Now, just looking at cantrips, then, if the caster regenerates 1pp per turn, we've got our status quo -- the caster can cast cantrips every turn, all day long.

If we stick with the 1pp/turn regeneration rate, let's look at how big the caster's power point pool should be.  It needs to be large enough that they can caster their highest level spell, but we want it smaller than, say, what a psion gets since it will regenerate much faster.  It probably needs to be a bit bigger than the cost of the highest spell, but only by a little bit.  Caster level plus one or two or three or ability bonus might be good.  Let's say it's caster level plus three, which is probably the same as caster level plus ability bonus for most low-level characters.

A first level caster would have 4pp.  And that the 1pp regen happens at the start of the turn, and only if the caster is below their full pool amount,  They could cast a three first level spells (assuming 1 per turn), and then be stuck with cantrips unless they went a round without casting.  Over an "adventuring day" of 6 to 8 encounters, that's a fair bit more powerful than a normal 1st level wizard or sorcerer, who could only cast 2 first level spells total.

At level 5, the caster would have 8pp.  A 3rd-level fireball would cost 6pp, and then the caster would have 2 rounds of 1st-level spells, and then be down to cantrips.  But the caster could have some more interesting choices to make: Maybe they plan on using 2nd level spells for the first two rounds of the battle, instead, or just use a cantrip the first round or two before deciding to use a 3rd or 2nd level spell.  This is getting closer to being in line with a regular caster's 9 1st-or-higher spells per day, but still likely above the average.

From the GM's point of view, this is quick-regen style caster class actually makes magic users little less of a wild card.  Regular casters can choose to blow through all their highest available spells at once, making the current encounter trivial but making a possible later encounter that much harder.  While that can be an interesting decision, it is often one that is made without meaningful information, as rarely do the characters have knowledge of exactly how many encounters they might face before having a chance to rest.  With a quick-regen power point pool, the caster will have their top spells available every encounter, but with a limit on casting too many of their high level spells in succession.

If your game contains both sections of single encounters separated by days of rest, as well as dungeon-crawls filled with many back-to-back battles, then I think you would see casters being on a much more even keel compared to martial types.

That said, what we've got now means that a 5th-level caster could still cast a fireball a minimum of once every encounter.  If 6 to 8 is the expected number of encounters in a day, that's way above the 2 times a regular wizard could do it.

Let's lower the pool threshold.  If we make the pool cap the caster level then the caster can't ever cast their highest level spells.  The could, then, have a once-per short rest ability that gives them a few extra power points and raises their pool cap temporarily (alternatively, it could reduce the cost of casting a spell, same difference).  With an average 2 short rests per day (plus the initial rest going into that day), the caster could now hit their max-level spell just 3 times a day.  This is getting closer to what we want.  Our level 6 caster, though, can still cast fireball every encounter, so let's tweak a few more numbers.

We want the highest level available spells to be only available with a 'boost" ability.  If we stick with the double-the-spell's level for the power point cost, then we want a 1pp limit at levels 1, and it being 1 less than caster level beyond first level.  The boost ability can give 2 or more power points (and is allowed to exceed the regular power point cap), so only when the boost is triggered will the caster get their highest level spells.

So, we've got a caster class that can use their highest available level of spell once each rest.  They'd be able to use spells below their highest level more often, but unless a fight runs long and the caster take rounds out to not cast anything, they caster will still be limited to a few of those bigger spells.

One drawback is that by giving cantrips a cost, a caster needs to not use them to rebuild their power point pool.  One of the design goals of 5e's cantrips was that caster could use them for reliable, stylistically-appropriate damage (instead of the situation where the magic user spends a lot of their time shooting a crossbow).  We could drop cantrips to having 0 cost.  A caster, once low on power points, would be able to then effectively alternate between casting cantrips and 1st-level spells, or stick to cantrips for a few rounds if they wanted to rebuild their pool.

One last consideration is out-of-combat spells.  If you feel that they need to be limited, you could assign certain spells a drain that reduces the power point pool cap by a point or two until a long rest is completed.  This would stop them from being able to be cast too many times a day.

Here's our final (for now) version:

---

Class level	Power points	Maximum spell level
1	1	1
2	1	1
3	2	2
4	3	2
5	4	3
6	5	3
7	6	4
8	7	4
9	8	5
10	9	5
11	10	6
12	11	6
13	12	7
14	13	7
15	14	8
16	15	8
17	16	9
18	17	9
19	18	9
20	19	9

Spell level	Power points
Cantrip	0
1	2
2	4
3	6
4	8
5	10
6	12
7	14
8	16
9	18

Features
Spell casting: You can cast a spell up to the maximum level listed, by paying the power points for it out of your pool.  If your start your turn below your pool's maximum, you regenerate 1 point.
Boost: You can cast a spell spending 2 power points less than you normally would.  This ability resests on a short or long rest.

---

Some other fun features might include stuff like reducing the cost of spells of a certain school by a point, or the caster being able to increase their regen rate occasionally.

I'll think about some more features, and hopefully try to playtest this a bit, it should be a class that better captures the feel of fictional magic users, but doesn't overshadow other classes (at least in theory).

Rest break

I'm not a huge fan of D&D 5e's rest mechanics.  Let's look at the why it's there, what it does, and some possible tweaks.

Why Rest?

Rests are part of the game balance.  Some characters have features that recharge on short rests, others on long rests.  Features that reset on rests are generally pretty powerful, so giving them more limited uses keeps the overall power of a class in more in line with those classes that that don't rely on those powers.  Long rest features are usually more powerful than short rest features.  These limited use features are "burst" abilities -- extra damage or healing or actions above what could be done normally.

In addition to the class (and some racial) features, rests also have universal effects like spending or regaining hit dice and health , removing exhaustion, etc.

On the player side, it helps stop certain characters from constantly overshadowing others -- a wizard that can cast their highest-level spells, every round, all day, would be pretty over-powered.  The choice of when to use these limited resources should be a fun and interesting decision-point for the player as well -- do they burn a big ability now, or save it for a more dire situation?

On the GM's side, the limited-use abilities are built into encounter creature and encounter balancing.  The DMG assumes an "adventuring day" is roughly 2-3 encounters, a short rest, 2-3 encounters, a short rest, 2-3 encounters, and finally a long rest.  More or less rests are going to decrease or increase the relative encounter difficulty, so you'll need to tweak the target encounter difficulty or adjust the effective creature CR.

Breaking Bad

Players are going to want to rest as often as possible.  Unless there is a reason that the characters shouldn't rest, it makes sense for them to short rest after every encounter, and do as few encounters between long rests as they can.  The GM can add limitations so that rests are limited, for example:

• time-sensitive goal
• rest interruptions, such as random encounters
• escalating threat
• limit on number or frequency of short rests (long rests are by default limited to once per 24 hours)

While some of these fit well into certain scenarios, they can easily not apply very well, and coming up with limitations on rests becomes a meta-game for the sole purpose of limiting what is often a mechanically-driven choice.

That's not to say that rests can't be a good part of role-playing or be story-driven (indeed, the party's conversation around the campfire can lead to awesome interactions and exposition), but the players' desire to trigger a rest is usually based on the idea mechanically regaining resources, and rarely for other reasons.

If there is a risk or cost (like random encounters, or the foes' power escalating), then it might seem like an interesting decision point, but are they?  Random encounters are usually just filler, extra work for the GM, and not usually advancing the progression of the party through whatever story they are exploring).  Escalating opponents fails to be fulfilling since it is a delayed (and hard to be viewed as causal), as it is not that rewarding to turn a tough fight into a TPK just because the party took a short rest several earlier in the session.

Once the party has access to rope trick or tiny hut or the like, it can be harder to control how often the party can rest.

If the party is resting too often, combats become too easy.  Sure, as the GM you can up the difficulty but that often means just making battles run longer, not to mention that you are effectively overriding the choices the characters make.

The DMG offers a few variant rules, namely increasing or decreasing the time needed for a short or long rest.  Increasing the duration of a short rest to 8 hours (and only once every 24 hours) puts a pretty hard cap on how often they can do it, but that also has a pretty significant impact on the feel of the game to be more gritty and less high-fantasy.  On the flip side you can shorten rests, but that makes them almost too easy to take.

You can use wave-based battles (essentially fighting two or three encounters back-to-back), but then you can have an "adventuring day" that is essentially:  Fight for a minute or two, rest an hour, fight for a minute or two, rest an hour, fight for a minute or two, wait 15-16 hours doing nothing, sleep.  Hardly heroic.

Restoration

How can we fix rests, then, or at least, what are some alternatives?

Can we just get rid of them? If we get rid of short rests, and just let short-rest abilities recharge when, say, you've been out of combat for x minutes, it's probably not too balance-breaking.  If the interval is too long, it can lead to more meta-game behaviour (like long waits between leaving a room just to hit the interval), so I'd be inclined to make it just a like 1 minute or 5 minutes of not running and nobody trying to kill you.  It does give a bit of a boon to classes that get short-rest recharges, though, as they will likely get them way more often.

If we wanted to keep everything in line with the suggested 6-8 encounters per day and 2 short rests, then we could just add a 2-rest limit:  So characters can take a short rest after they've been out of combat for 1 or 5 minutes, but they can only do at most twice a day.  It adds another thing to track, but other wise preserves the intended balance.  It still doesn't stop the players for pushing for a long rest, though.

Another method might be to just to tie rest effects to XP gains.  If you divide the XP required to level by 12, and trigger a short rest every 2 increments and a long rest every 6.  It's a fair bit more work to track, though, and will get crazy if you have characters at different levels.

What if we combine the ideas and go just by level and not XP?  So when a character levels, they get two long rests tokens (or points or whatever you want to call them), and 4 short rest tokens.  They can cash them in any time they are out of combat for 1 or 5 minutes or whatever.  This gives players the interesting choice of when they can use them, but still puts hard cap on how often they get used.  Optionally, the GM could then reward extra for certain in game events, or force them to be spent (like force a long rest to be spent when a series of encounters is over at what is clearly the end of a day).  I'm not sure if taking the choice out of the players hands that would would be too frustrating for the players or not.  Another alternative would be to give to tokens to the party as a whole, and they'd have to come to some consensus as when to use them.

I haven't tried this idea yet, but will run it by my players to see if they want to give it a go.

Tuning Your Role-Playing Game's Parameters

You may not realize it, but your RPG has a number of parameters, and the difference between expected and actual experience of those parameters is likely the biggest factor the players and/or GM not having a good time.  By managing expectations and getting feedback on these parameters, you can makes sure you and your group has a better game.

The D&D 5e Dungeon Master's Guide's "Know Your Players" section gives GMs a starting point for tuning they game experience for their players, but I think the approach detailed here supplements that guidance, and will lead to a better gaming experience.  Thinking about these options as tune-able parameters will help that -- instead of trying to pigeonhole players into an archetype, figure out what are the parameters that matter most to the individuals and the group, and tune the game towards them.

What are "game parameters"?

Your game has a number of dials or controls.  They are the theme or tone of the game, what rules are firmly adhered to and which can be bent, the amount of humor, the gritty realism, the level of fantasy, and the ceiling for impossible actions.  They can include binary options like whether there is PvP combat, or they can exist as some point in a range between two extremes, like serious vs. silly.  They can cover how the group divides its time between combat or RP-based encounters.  Some are controlled by the players and only loosely defined or steered by the GM, and others the GM exclusively controls.

The game system itself might define some of the parameters, or at least set baselines for them.  Others are set by the players and/or GM.  Some emerge dynamically as a campaigns plays out, and will fluidly change from session to session.  Others will be constant, perhaps for the system, the campaign, or the group.

It would be impossible to list them all, but let's look at some common and/or important ones for a game like D&D 5e (with some other games mentioned for comparison):

Combat vs. role-play

The division between combat encounters and role-playing is probably one of the easier things to tailor to your group, and one that players can feel diversely about.

Combat style

Tactical grid-based combat or theater-of-the-mind?  Or maybe something in-between, like zone-based combat.  Not every encounter needs to be the same, sometimes the encounter can lend itself to one style over another, but it's good to know your players' preferences.

PvP

Whether PvP is allowed (and if so, under what circumstances), or even things like allowing intentional friendly-fire for area-of-effect spells.

Inclusion of sensitive topics (rape, torture, gore, etc.)

Especially important when playing with people who don't know each other well, make sure everyone knows where the line is for sensitive topics, and what is allowed and what is not.

Silliness

A D&D game might hardly be a D&D game without a Monty Python or Adventure Time reference somewhere, but sometimes you need to disallow a familiar being named Dickbutt or a character named Tronald Dump when you know it will only break immersion after the initial chuckle is gone.

My Gamma World games are inherently more silly than my D&D games, and that's part of the appeal for when we run it.  For some parameters, like this, the system can set the baseline in very different spots.

Single character spotlight vs. the group

This might come under splitting the party, or even just players talking about how their characters spend their downtime.  Know what the threshold is for you and the players is for focusing on activities that aren't including the whole group.  Some activities like this can be dealt with between regular sessions with just the individuals in question.

Lethality

Whether you the GM rolls their dice in the open or not, and how hard you play the monsters to take down the characters. I feel, that when I GM, if I'm not rolling dice in the open, there's no point in rolling -- but I'll tweak less visible aspects (like monster HP or tactics) if I've misjudged an encounter's intended difficulty.  My goal is to make the players have fun, but rolling the dice in the open is a way to keep risk in the minds of the players.

Some players are more attached to their characters than others, and will be more upset by character death.  It's a good idea to know how the players feel, as well as to set their expectations of the game you intend to run.

Intra-party conflict

Along the lines of PvP, but you might want to include discussion about non-combat actions, like stealing from the party (I'm looking at you, stereotypical rogue player) or conflicting alignments/goals.

Realism

Is the basis in reality in your game more akin to Crouching Tiger, Hidden Dragon or Heat? The system will often have its own anchor on the reality scale, but you can always push that up or down.  Some character concepts may hinge on a being able to operate on the envelope of what is allowed, so it is important for players and the GM alike to be in accord.

How (or who) makes decisions for the group

This is one dynamic that the GM doesn't really control, but would be wise to pay attention to.  Does the group vote on decisions, to work until they have consensus?  Does a single player (or character) dominate the decision making, or is there anyone that routinely is excluded from getting what they want?  Some players may not care so much, but make sure the ones that do are getting what they want.

Creative contributions

Can the players freely contribute their additions to the world's history, events, places, and people?  Or, as the GM, do your prefer to keep narrative control to yourself?  You'll have to weigh your comfort with being able to assimilate new ideas with the players' desire to collaborate in world-building.  Games like Dungeon World rely on player contribution, but not all players want that responsibility.

Rule flexibility

Are you playing strict rules-as-written?  Following guidelines like Adventure League when it comes to supplements?  What homebrew and houserules do you have?  Are you including Unearthed Arcana or DM's Guild material?  Extra rules options can tax the GM, but give the players more options. How flexible are you with "the rule of cool" and letting the characters pull off stunts beyond what the rules allow?

Rewards and pacing

How much treasure and how many magical items do you reward the party with?  Do you follow by-the-book XP rewards, or use milestones, or something in-between?  The feeling of character progression in terms of gear and level is important.  Does the system have a "sweet-spot" where you want to slow progression a bit to spend more time there?  Does the player have a specific item in mind that is part of their character concept and goal?

Puzzles and problem solving

Some players thrive on solving puzzles or coming up with creative solutions, while others will be easily frustrated and quickly become disinterested when they feel "stuck" for any length of time.

Repercussions

Will characters get away with breaking laws or violating customs?  Sometime the players just want to play murder-hobos, but sometimes they want a world that reacts to their transgressions.

Remember, this is by no means an exhaustive list.  Not all of these parameters will matter to your group or game, and you will certainly find ones that aren't on this list that matter to your group.  But you should figure out what the important ones are.  And here is why:

Expectation, importance, and experience

Most of the time that there is unhappiness or dissatisfaction at the table, it likely stems from someone's expectation of one of these parameters not meeting what they are experiencing.  Certainly, people can be pleasantly surprised when the is a disconnect between expectation and experience, but it can also lead to disappointment. If the person has attached importance to that expectation, that disappointment will mean a greater level of dissatisfaction.

Ideally, for each parameter you, you should ask each player what their desired level is and how important that parameter is to them.  In an ongoing game (or in retrospective), you should also ask what they perceive the value to be or ask if it needs to be dialled up or down, relatively.

Not everyone in the group will have identical desires for every parameter, but hopefully your group's range of desires falls within a close range of values.  Depending on what it is, though, it can be okay for there to be wildly different values.

Group vs. individual parameters

Even if your players have some wildly inconsistent expectations, that is not always a problem.  Some parameters are easy to fine-tune or have different settings for that player.  For example, if only one player gets a lot of enjoyment out of creative contributions, then don't force prompts for that on the other players.  If one player wants extra solo spotlight time or to be able to do stuff on their own, then see if you can handle that between regular sessions.

Values change

It is important to remember that any of these parameter can change.  Players may evolve different tastes, and the focus of a campaign my drift over many months.  Game systems that lend themselves to one play-style in the beginning may be more rewarding played differently at higher levels.

After each session, evaluate where the game hit the mark and where it missed, and make yourself a note of what to adjust for the next session.  It's not hard to fine-tune towards your marks this way.

Periodic re-calibration is a good idea.  Give your game a tune-up by checking in with the players every now and again to see where things stand.

For game masters

The first step is to find out what is important to your players, and to yourself. Explore and set expectations at the beginning of a campaign for yourself, and find out what the players are expecting and wanting.

Set the dials for the game, and tailor to individual players where possible.  Think ahead if any parameters are expected to adjust during certain portions of the campaign.

Recheck periodically, and make sure you are checking the right things.  You can do it more formally with something like a survey, or just check-in with players pre/post or between sessions.

For players

Make sure you are clear about your expectations, as your GM can't fix/adjust what they don't know. If there is a gap between your expectations and experience, bring it up sooner rather than later.  Keep in mind that other players have their own expectations, and GM may be trying to find a happy medium.  Contribute to that effort.

For audience

These days, with Critical Role and Acquisitions Incorporated, Twitch and YouTube, simply watching RPGs is a lot more common than it used to be.  It is important to remember, that as audience or viewer, you may have different expectations and desires than the players and the GMs of the games you watch.  Moreover, viewers are less likely to be privy to discussion about the parameters.  Before you get upset about how someone else is playing their game differently, remember that even in the most rigid of rule sets, there will be variation in how different groups play.

Summary

By thinking of the game system and sessions as something that has qualities you can tweak and adjust, it's easier to identify what the GM and the players want out of the game, and whether the sessions are hitting or missing those targets.

The targets can (and will) change over time, so it is important to continually adjust with them.  The good news is that all of this is easy, and doing so will make for a more fun game for everyone.

Taking risks

"Sometimes you gotta drive your character like they're a stolen car" - Adam Koebel

One constraint on players' play is the fear of a sub-optimal move. While often the defining characteristic of the power-gamer archetype, this trait can just as easily show up with players who have a more role-playing focused play-style. I can only speak for my group, but coming from years of more tactically-heavy D&D 3.5 games, as well as computer and board games where the main goal (winning the game) relies on making optimal choices, it is often hard for some (myself included) to let go of that mindset.

5e tried to fix this a bit with the inspiration mechanic - sure, you are making a sub-optimal choice, but if it's in-character and/or meshes with your flaws/bonds you get a mechanical reward in the form of inspiration.  That carrot goes away if you already have inspiration, or your flaw/bonds don't really fit the situation, or the GM isn't on the ball all the time about rewarding it (something I am certainly guilty of). Without consistency, it's not a good incentive, and by making it a mechanical reward, you are just pushing the optimization decision to be trying to calculate if the value of the reward outweighs the cost of the tactical choice.

As a GM, one (previously huge) peeve of mine is the player that starts making a move or action during their turn, and then wants to re-choose their actions because they started moving and then saw something around the corner, or realized they couldn't move as far as they wanted, or were going to make it within a ranged they needed.  I used to make them stick to their original action (unless the choice was clearly from some ambiguous or incorrect information on my part), but really I don't bother forcing the issue any more:  They are just going to get miffed about being made to have sub-optimal turn.  If that's how they derive their fun from the session, I'm not inclined to put the brakes on it unless it's infringing on someone else's fun.

Some players just get that they, like their characters, are going to have imperfect information and will make bad choices because of it.  Other players aren't going to be satisfied unless they achieve as much as mechanically possible each turn.  I'd say my current group is a pretty even three-way split, with some players at opposite ends of the spectrum, and some that have a hybrid approach that puts them in the middle. Switching away from grided combat seems to help to some degree, but the tactical crunch of D&D combat is a pretty big factor in the game's appeal for many players, so even that is a trade-off.

Eventually, the decision about how to play is going to have to come from the individual player - the biggest risk you can take with your character is not making the "best" choice, but picking something else because it is fun, or it is just what the character would do, or it's just going to make the story more awesome.  As a GM, the best incentive you can provide is making the results of those choices as fun as possible.  If the players start to see that their risky choices can lead to more fun by picking something other than mechanical optimization, then risky becomes the best choice.

Crabjack-21 - An update to the polyhedral dice gambling game

Crabjack-21 is a dice-based gambling game that uses a single set of d20/d12/d10/d8/d6/d4 dice, so it can make a nice fit for an RPG setting using something the players have on hand.  It's based of off Crabjack, but adds the d20 and has the payouts balanced to account for the extra die and higher total.

Crabjack-21 is played by a single player against the house, although any onlookers might make side-bets with each other about the outcome of any next roll.  The player makes their initial bet (within the house limits).  From now on the player is going to pick a die and roll it, adding it to their running total.  Each die can only be rolled once.  Depending on the total they are at, they will either win a payout (ending the game), bust out (ending the game), or have to keep rolling.

Getting an exact total (of all dice rolled so far) of 7 or 11 or 21 wins a payout.  The player busts out if they go over 21, having a total of 22 or higher.  If the player manages to roll all six dice without busting out, they win regardless of their total.  Some versions of the game (you can pick which version you like, or have multiple versions in your world representing local variants of the game) have special rule if you roll a 1 on the first roll:  It can immediately end the game (with or without a payout).

Here are a couple versions of the game, these all have a base payout of the bet plus half, and then a bigger payout for the 6-dice win:

1 (1st roll): Keep rolling
7 or 11 or 21 (1st to 5th roll): 1.5x
21 or under (6th roll): 2x

1 (1st roll): End game, lose bet
7 or 11 or 21 (1st to 5th roll): 1.5x
21 or under (6th roll): 6x

1 (1st roll): End game, but get half bet back
7 or 11 or 21 (1st to 5th roll): 1.5x
21 or under (6th roll): 5x

Outside of a casino-like environment, gamblers can take turns being the house.  They should agree on each taking the same bet and number of turns being player and house.  If played this way, you can can tweak the payouts to whatever you want, e.g. 2x on 7/11/21 and 10x on a 6-dice win.  Those higher payout numbers would make being the house all the time a losing proposition (with perfect play), but it doesn't matter if both sides take turns playing the same way.

Crabjack - A polyhedral dice gambling game

Crabjack is a dice-based gambling game that uses a single set of d12/d10/d8/d6/d4 dice, so it can make a nice fit for an RPG setting using something the players have on hand.

Crabjack is played by a single player against the house, although any onlookers might make side-bets with each other about the outcome of any next roll.  The player makes their initial bet (within the house limits).  From now on the player is going to pick a die and roll it, adding it to their running total.  Each die can only be rolled once.  Depending on the total they are at, they will either win a payout (ending the game), bust out (ending the game), or have to keep rolling.

Getting an exact total (of all dice rolled so far) of 7 or 11 wins a payout.  The player busts out if they go over 11, having a total of 12 or higher.  If the player manages to roll all five dice without busting out, they win regardless of their total.  Some versions of the game (you can pick which version you like, or have multiple versions in your world representing local variants of the game) have special rule if you roll a 1 on the first roll:  It can immediately end the game (with or without a payout).

With that framework, there's a lot of possible payouts you can use to get a respectable game -- one that has close to even odds that still slightly favour the house with optimal play.

Here are a couple versions of the game, these all have a base payout of the bet plus half, and then a bigger payout for the 5-dice win:

1 (1st roll): Keep rolling
7 or 11 (1st to 4th roll): 1.5x
11 or under (5th roll): 15x

1 (1st roll): End game, lose bet
7 or 11 (1st to 4th roll): 1.5x
11 or under (5th roll): 50x

1 (1st roll): End game, but get half bet back
7 or 11 (1st to 4th roll): 1.5x
11 or under (5th roll): 40x

1 (1st roll): End game, but get all of bet back
7 or 11 (1st to 4th roll): 1.5x
11 or under (5th roll): 25x

The third version, with half the bet returned on a 1, is close enough to an even payout with perfect play that two players could take turns being the "house" outside of a casino-like establishment.  Lack of perfect play will give the house an edge, though, so players should at least agree on an even number of turns.  The second game has a payout of 99%, and the other two are around 98%.  Really, alternating house would work pretty well with any variant -- it probably depends whether you just want to have the players rolling dice or yourself as the GM.  The first version probably makes the most sense for a smaller "back-alley" games, with the lower 5th-roll payout requiring less of a safety-net bankroll.

Update: Check Crabjack-21 for a version using the d20!