Backloggery

"What you need is a little motivation. What gamer doesn't like to look over their stats and celebrate the milestones as they progress toward a goal? That's where we come in. We'll keep track of everything for you so you'll know what you've done and what still needs your attention."

Urgh, I'm afraid to use this. I don't beat games, ever.
Plus, what about fighting games? Aside from unlocking all of the characters, there's no real way to 'beat' them. (just pondering completing all of the challenges in KOF XI is terrifying)

If you are braver than I, go check out The Backloggery