Well, I went ahead and finished my list already. I might switch the order around a teensy bit here and there, but I'm pretty sure I've narrowed down everything I want to include on this list. I'm mildly worried that I'll get tied to a stake before I get to finish it, though, since four of the games in the first tenth of my list happen to be some, uhh, pretty big names. Ones that you could usually expect to see at the opposite end of the list. And the fifth... is a browser-based Flash game. (Oh dear.)
Just to make sure: free-to-play browser games are still fair game, right? It's not like it's fucking Candy Crush Saga.