I have pretty broad tastes when it comes to games - I'll play just about anything - but if there is one thing I know absolutely hooks itself into my brain and will get me to obsess over almost any game it's
COLLECTING STUFF THAT I CAN GET ONE OF EACH OF
there's nothing that scratches my brain more in Just That Way than a game that lets you collect a really large number of unique Things.
- Weapons (especially if those weapons evolve)
- Abilities/Martial Arts Moves etc
- Pocket Monsters
- Pieces of your town that a genie blew up
- Anything that there's room for exactly one each of in some sort of bank or vault or stash
I don't know what it is about this particular mechanic but something in my brain goes brrrrrrr at this concept