Things I like from games I've been playing:
WFRP 4e: Opposed Checks for attack rolls. Hey, why do we have a separate thing for "contest of strength/wills of two people" and we don't use that for, you know, a contest of arms.
WFRP 4e: Social class as a ranked stat. Making society... matter... who knew...
Battletech: movement, combat, and damage phases. One of the only games I know where the first person to go is at a disadvantage. Avoids first turn advantage AND being bored when it's not your turn.
Settlers of Catan houserule: everyone has visible resource cards/open information One of the high level skills of Catan is that you can suss out exactly what everyone's hands are if you pay attention. If you make the hands open, everyone acts on high level information anyway and the game becomes incredibly strategic and there's less victories "out of nowhere."
Doom clocks and doom tracks: many games. I love basing things on clocks!! Time for event. How much you need to get a thing done. It's good.
Environment matters: Roadwarden. A game on a 40 day clock, clearing roads for faster travel, securing spots for sleeping and clean brooks to bathe matter to an amazing degree.
game mechanics are all about abstractions of something. To understand what a mechanic or system is doing, you have to look at what it is a simplification of first.
HP is a very high level abstraction of the physical state of an entity and as a result often the last point matters mechanically. Turn HP into a damage track or have additional effects as the HP value decreases and suddenly you have a much more characterful system that isn't reducing something incredibly complex to a binary state.
Damage calculations are a constant source of complexity and woe. If they are too simple they flatten something as complicated as the physical interaction between two entities into an accounting problem. If they are too complicated you will get bogged down in calculations and make it impossible to understand where numbers are coming from. Think about what kinds of entities are interacting and if there's ways to model a gunshot or sword slash that don't involve randomizing damage with extra rolls of the dice.
Go research things beyond games! find inspiration in games then ask why they chose to do things in the way they did! If you want to import someone else's assumptions, make sure you know what they were!
