One thing I've realized about my own games is that my ability to daydream, think of cool stuff, embody NPCs and have fun playing the game is closely tied to how frequently the responsibility to come up with something new shifts to the me.
Mechanics around racing for RPGs. Text that teaches vs. text as reference. Lull between character creation and play. Do mechanics determine theme? Mechanics to foster player to player (instead of player to GM) interaction. Good stuff!
I've been playing a handful of OSR games chasing a particular experience: quick to start, easy to understand, fast resolution, compelling abilities, long gameplay possibilities, etc.