I do enjoy game mechanics that interact in emergent ways that weren’t fully planned out by the developer in games like Dwarf Fortress.
Inventory Tetris
Ew, please no. I’m pretty much the exact opposite, I’d rather have little or no need for inventory at all. As in, more Zelda, less Diabo.
I could go on a 6 paragraph rant about Breath of the Wilds inventory system.
Roguelikes and roguelites tend to be my favorite. Ones where each run is new and you can toy with different builds and usually get pretty OP toward the end (or get cut down early because luck wasn’t in your favor or you made a mistake).
If you are at all (or were ever) into pokemon, have you played through Pokerogue.net already? Game is hard!
I love anything with a tech tree or a skill tree or items that improve based on usage. The ratchet and clank games have such a great mix of all of those things, I end up spending a bunch of time just leveling up the guns!
Parry and riposte mechanics make me happy. Idk why exactly, but something about timing a parry and making the enemy entirely helpless for the followup is just great.