In my books, a series counts as one.
10: Risk ( It's a classic, no really. You've gotta give it props - it's the only board game that can really get fun.

)
9: Megaman X (2D series - the 3D one stinks. )
8: Street Fighter 2+ - without this, we would have HAD no good platform fighters. This is THE platform fighter.
7: Warcraft 1, 2 (3 ... maybe. Erm... no. They killed it. )
6: Diablo 2
5: Quake 1/2
4: Battlefield 2
4: DoD/DoD:S
3: STARCRAFT!!!! [ OMG STARCRAFT!!!!]
[ This is such a tough call. If I were to score these two on a scale of 1-10, I'd give one a 9.99, and the other a 9.98. ]
2: Final Fantasy 6 [ The titles in this order: 6, 9, 7, 8, 5, 4 - and no other ones. I never played 12. FF8 gets too harsh a bashing. It's a good game - it's just before its time - even I didn't like it on the original release. Put it in today's context - it was good. ]
1: Chrono Cross / Chrono Trigger
If you think of runescape as a big chatroom instead of a game, it's not half bad.
lol.
Seriously ... they've got to do something about that music.
You know Neverwinter Nights? Imagine Runescape with the graphics and music of that title. Then what? It would rule. It's got the makings of a great game, it's just got graphics that are ... erm ... er ... no comment.
BUT - there's a plus for it right there. Though Runescape does have garbage graphics - you've got to realize not everyone has a gaming system, or a parent who will shell out cash for gaming gear, OR a Job to get parts for gaming gear ( like, you're still in elementary or middle school. )
For those folks out there - Runescape offers an option, and some halfway decent play to boot. It's BETTER than some games I've paid for. And that says a lot. So, I give Runescape some credit - it deserves it.