We all have them. That thing (or things) that makes us want a game, even if it sucks. Maybe even defend a terrible game, just because it features that one thing. Here are a couple of mine.
Parkour:
From the first time I played Mirrors Edge, I was hooked. As far as I'm concerned, that is the best game mechanic ever. Unfortunately, there aren't a lot of games the make use of any sort of parkour, or free running. The only ones that i can think of other then Mirrors Edge, are Brink and the Assassin's Creed series.
Being stranded on an island:
Even less utilized then parkour, the only games really are the Lost in Blue games. I wish someone would just make a realistic game that just sort of throws you on an island, with the only goal being survive. No weird puzzles, no weird, ancient civilization, just survive as long as possible.
I know you have your own, so lets hear them. I won't hold it against you. ;)
Also, if you know of any game featuring mine PLEASE TELL ME!!!