here's a bunch of weird answers! i like when a 3d-platformer isn't about precision platforming! i just want to jump around and collect a thing! (Super Cream 64 is great for this because it just, adds a bit of flight to a game designed without it)
i like when an rpg has a good flow to it. like, p3p let me enter a flow by just like, fully separating the rpg part from the rest of the game, so i could blast through several in game weeks of "well, just one more day before i put it down for tonight" while also letting me go "okay, time for 4 hours of dungeoning with no cutscenes, let's listen to youtube videos/podcasts". other games can do this by just like, being well balanced to avoid grinding, and doling out story over shorter bursts than like, 20 minute cutscenes.
and finally, i love when gamedevs just like, put in their favorite little ocs and/or their friends' favorite little ocs (again shout out to Super Cream 64)
