I collect tabletop role playing games. I don’t really play them much any more. But I can’t help but mess with the rules. I get more enjoyment out of that than actually playing most games.
Dice: TTRPGs use dice, except for those heretical diceless “games”. It’s not that hard to use words properly. One die, many dice. No, I don’t care how many people are using them improperly. They’re all weak and stupid. The standard sizes of polyhedral dice are d4/d6/d8/d10/d12/d20. A d2 is a coin flip. A d3 is a d6, halved.
Advantage: Roll two dice, take the best result.
Disadvantage: Roll two dice, take the worst result.
Bonus die: Roll an extra die and add it to the result.
Usage dice: You use a die size to track some expendable resource, like torches or arrows. Every time you might use some up, you roll the die. On an appropriately low result, you reduce the die one size. When you reduce the smallest sized die, you’re out of that resource.
Hit points (HP): How you character keeps going in combat. They’re a combination of skill, luck, and determination. They’re NOT actual body mass, except for some monsters. Generally speaking, most TTRPGs use different sized dice for different classes/professions of adventurers, and add dice as your characters progressively gets more experienced.
Some games use nothing but d6s. That’s fine. You can still have variety in outcomes. For damage effects, you can use disadvantage for minor hits and advantage for major hits. For rolling hit points, you can use this fun little chart:
Fighter: I am mighty! Roll with advantage.
Thief: I play the odds. Roll three dice, take the middle result.
Cleric: I accept my fate. Roll one die.
Wizard: Wait, what? Roll with disadvantage.
You can employ usage dice for hit points, advancing the die size as your character levels up. Fighters reduce on a 1, thieves and clerics on 1-2, wizards on 1-3. A minor hit rolls with advantage, a major with disadvantage.
Luck: This is a personal favorite. Whenever appropriate, but at least once per combat, each character rolls a d12 luck die. They then check their character sheet, where they track their luck scores. Good luck starts at 12, and decreases. Bad luck starts at 1, and increases. If you roll well with your luck die, you get a boon. You you roll poorly, you get a bane. Hedge witches and priests can curse and bless you.
Many RPGs use a d20 to determine success. Most of those use 20 as the best result. These are roll-over systems. Some of them use 1 as the best. These are roll-under systems. Both use target numbers to beat, and you add or subtract modifiers to see if you succeed. If you don’t want to change the result of the die roll, you change the target number instead.
Blackjack system: This is a roll-under system where you have a number you need to roll under, like your fighting ability, and also a target you need to roll over, like the combat ability of your foe. You want to roll high, but not too high.
Opposed rolls: Sometimes, you don’t want to roll against a fixed number. You roll against your opponent’s roll. This is generally used in player versus player combat, but it can be used as a general mechanism. In every challenge, your character and the foe/obstacle they face both roll. It may be one roll, winner take all. It may be a multiple die roll grind. Each side may even roll multiple dice (skill + tool, for example), either adding them together or taking the best. The multiple dice version gives good averages while also making it possible (but unlikely) for a novice to beat a master. It’s also easy to give fine grained results by varying each die size, say a d6 for skill and a d10 for the tool. You can even use dice for the situation or environment, like for the range and cover of the target of a bowman.
