I beat I Wanna be the Guy on normal mode once. That alone should quallify me as being "good at gaming".
Edit: I also beat the secret area in Twilight Princess, the first Pit of 100 Trials in Super Paper Mario, the Hag 1 in Banjo Tooie, Boss Battles on Intense in Super Smash Bros. Brawl, all the arena battles in Ratchet and Clank: Going Commando and Up your Arsenal on both the normal and New Game Plus difficulties and got all the power cells in Jak and Daxter.
Edit: I also beat the secret area in Twilight Princess, the first Pit of 100 Trials in Super Paper Mario, the Hag 1 in Banjo Tooie, Boss Battles on Intense in Super Smash Bros. Brawl, all the arena battles in Ratchet and Clank: Going Commando and Up your Arsenal on both the normal and New Game Plus difficulties and got all the power cells in Jak and Daxter.