Still drawing from that idea document that I maintain, these are further game mechanic ideas that I like. Feel free to take these, use them, adapt them or hack them for your own games.
Advantage and Disadvantage with Fate Dice
As written, Fate Core allows you to use Aspects to add a +2 bonus to rolls after the fact, or to re-roll. I thought of another way to represent an advantage in a Fate roll, this time before the fact. In some of my Fate-based designs, I have a player set aside one of their four dice, and set it to a “+” or “-” ahead of time. This not only grants a bonus that is approximately equivalent to the +2 from an Aspect, it also reduces the amount of swing that is possible in the roll. With only three dice, the worst that can happen with the advantage is that three dice come up “-“, or a total of just -2. I also like how visible the bonus (or penalty) is on the table, and I think of it as similar to D&D 5th Edition’s advantage/disadvantage mechanic.
Using the Force or Magic Skill
One of the things I like about skill systems in RPGs is when you have to make a limited number of selections from a list, all of which are desirable options. (No dump stats or skills in our designs, please) One of the things I’d like to see more explicitly is treating magic, or whatever your equivalent is, as a skill, meaning that you have to commit time and practice to magic, and that time and practice does not go elsewhere. You have the super-skill, so you lack the other skills a mundane person would have.
Specifically, I have in mind Jedi in the Star Wars universe, who tend to be better than everyone at everything, and to also have magic powers. Rey is an example of this, but so is Luke, and Anakin or Obi-wan before him. They are fantastic at every action-hero thing they try, and also have the Force on top of that. I much prefer Force-users, or magic-users, as specialists who have an arcane, occult, rare specialty, and I think that games should reflect this by making the choice to have magic powers a choice with a cost.
I have an idea for a game from the point of view of elves, or of other beings who have very long lives compared to humans. In this game, there will only be three levels of skill to reflect the kind of mastery an elf might achieve (assuming D&D elvish lifespans): one year of skill, ten years of skill, and a hundred years of skill. I like there being a level of mastery that is simply unattainable for shorter-lived beings, and also reflecting the idea of some diminishing return in gaining skills. The differences in skill become very small at the highest level in any field, it seems. But I like the idea of a setting where these very long lives matter, and where the most highly skilled elves could simply clown the most highly skilled humans or others. It’s a challenge to build a game around this fundamental unbalance, but is fun to think about.