Super Meat Boy.
The game is hard, but I don't know if I have the skills and/or the patience, but I seriously enjoyed that game, I even got all the bandages from every level, unlocked every character and finished every single level with A+, secret levels and nightmare levels included. And I'm considering a second playthrough. From scratch.
In fact, ever since the Nes and Snes era, I'm simply awesome at any platformer, mainly in 2D or 2.5D.
3D platformers are generally very easy for me.
Also, I was pretty awesome at F-Zero GX and I was pretty proud of my cutom built ship. Still my favorite racing game of all time. I miss that game.
Aside from that, I don't "pwn" every shooter I play, but usually I'm one of the better player of almost any match, especially in team-based shooters like Wolfenstein: Enemy Territory, Team Fortress 2 and Tribes: Ascend. I'm especially good at CTF.