Oh I have to disagree. Angry Birds was kind of the introductory game for many gamers who started on mobile platforms. Not the "best game ever", but in terms of impact, i'd rank it very high. WoW would rank among the TOP 20 as well since it revolutionized the MMO genre and got a huge player base, as well as becoming part of pop culture. Don't know where I'd rank Final Fantasy, since it very much defined the roleplaying game genre.
Now where the hell is TETRIS?