I’m fascinated by how all the different role-playing systems handle common tasks in different ways.
For example: the “help” action.
D&D: if you help someone, they roll with advantage. Instead of rolling the usual 1d20 plus bonuses in order to meet or beat a difficulty class (DC) or armor class (AC) number, they roll 2d20 and take the higher of the two (twice the chance of success!). The only thing you spend is time: this will use up your action in your turn, if in combat.
Dragonbane: Like D&D, help only costs your action, and they roll with advantage, which Dragonbane calls getting a boon. The difference here is that you have to roll at or below your skill level to succeed — a roll under system, not a roll over system.
Cypher System: if you don’t have an inability in it (i.e. are bad at it), you can ease the task for someone else’s d20 roll by one step — two if you’re trained or specialized in it. Each step translates to 3 points in the target number (TN), so easing the task by two steps changes it from difficulty 6 (target number 18) to difficulty 4 (target number 12). As with D&D, help only costs your action.
It’s also possible for you to perform a complementary action instead that eases someone’s else’s roll.
Avatar Legends: you can mark 1 fatigue and make the Basic move help a companion. This only improves their roll by 1 point, and so it’s only useful if they missed the roll with a 6 — where a +1 turns it into a 7, a weak hit — or got a weak hit on a 9 — where a +1 turns it into a 10, a strong hit.
Unlike other systems, it is done after the roll.
The One Ring: first, some background: TOR has aspects of roll over games and dice pool games. For a skill check, you roll a Feat die (a d12 with some special values) and a variable number of Success dice (a d6), and add them up. If you roll a 6 on any of the d6s, that is extra successes.
Now, on to the help details: you support someone by spending a Hope point (a somewhat limited resource), which gives them an extra d6. Also, you must have a rank in the skill you want to employ to help them, similar to Cypher System, where you can’t have an inability in the skill.
Star Trek Adventures: again, I’ll start with some background: Star Trek Adventures is based on the 2d20 system, which, like The One Ring, is another kind of dice pool hybrid. It uses d20s instead of d6s; for each d20 result, it uses roll under rules to see if that roll is a success — but after that, you only care about the number of successes, like a more traditional dice pool game.
Your helping someone is called teamwork, and multiple helpers are possible, if discouraged. You roll a single d20, and if it succeeds, you can add that success to the successes of the person you’re helping — but their roll only succeeds if they get at least one of their own successes.
Vaesen: in our first standard dice pool game, you generally roll your Ability + Skill number of d6s, and each 6 rolled is a success. You and up to 2 other characters can help someone with their roll, and each person helping adds a d6, up to 3d6. No cost for helping is mentioned in the rules at all.
Candela Obscura: also a d6 dice pool game, but you generally roll fewer dice than Vaesen, and there’s the concept of a mixed success on a 4–5 result. You help someone by spending 1 drive point (a limited resource) to add a d6 to their roll. You can only spend 1 drive point, and doing so opens you up to shared consequences if the roll goes poorly — since the GM never rolls, bad things only happen as a result of your rolls.
If multiple people want to help, it becomes a group roll, though it’s still only one person rolling and the others contributing. The dice pool also maxes out at 6 dice. (The subject can also spend their own drive points.)
Blades in the Dark: has the same dice rolling mechanic as Candela Obscura (which is based on it). To help, you take 1 stress, and only one person can help.
If someone is already helping, you can perform a setup action instead to help indirectly, similar to Cypher System’s complementary action.
Star Wars: again, I’ll provide some background first: Star Wars is a dice pool game, but the d6/d8/d12 dice have their own special positive and negative symbols on them rather than numbers, which you add up to determine the outcome. Assisting someone else is a maneuver, rather than your main action. Your assistance adds a bonus die (a d6 with positive symbols) to that person’s dice pool. Multiple people can provide assistance.
Whew! These are just the games I’m personally familiar with. I’m sure there are a lot of other variations out there.
It’s especially interesting how much or how little you can help. Sometimes, it’s doubling the chance of success. Sometimes, it’s just nudging things the tiniest bit.
And in the best examples, the way you help is inextricably linked to the unique features of that game, whether it’s a roll over/roll under game, a dice pool game, or a hybrid.
One last thing to note: in most systems, it is explicitly stated that the GM must approve the assistance attempt, and the player must explain what steps they’re taking in-game to provide the help. You can’t just say “I’m helping” — you have to say how.