Eh, probably beating some guy who was hogging and essentially bullying people on the Street Fighter 2 Machines finishing him off with a perfect then leaving my game to the rest of the younger kids there looking to play.
Not really a completeist or anything like that.
Gaming challenges now are more self imposed things like "Play Fallout 2 roleplaying as Batman." (IE Unarmed/Stealth/Throwing Weapons).
Or "Play 9 games of Fallout 2 as the Team Fortress 2 characters, changing between characters every 3 levels."
Demoman being the hardest by the way... due to the lack of explosives and pretty much everyone in TF2's lack of allying up with people.