Mass Effect is worth 100$.

 yea in mexico? lol

Gears of War 2 has a surprising amount of haters but, to me, it was worth buying the console AND the game.

Lost Odyssey and Halo 3 round out my top 3 picks.

Halo 3 is the obvious choice.

Lost Odyssey, Gears of War 2 has made me more angry than anything else in the world, even more so that Chelsea being robbed of their place in the champions league final

you're talking about xbox 360 exclusive games or every game on xbox 360?
for me: Halo 3, Burnout Paradise, Crackdown, Ridge Racer 6, Tales of Vesperia, Saints Row 2. the best part is that none of those games cost 60$ anymore(you can buy most of them new for less than 30$) and they will take a lot of time to finish them and then there's multiplayer in some of them. i would also recommend Dead Rising - really cheap and fun game. despite relatively short single player(lasts 8 hrs maximum) there's plenty replay value and you will be going back to this game just to slash zombies for fun.

Orange Box
Mass Effest
Command and Conquer Tiberium Wars
Bioshock
Gears of War 2
Oblivion
Fable 2

so you're talking replay value only? (you're saying the game sits there without talking of how long it took to fininsh in the first place).

in that case you'll be stuck with online games (Halo, Gears.... unfortunately, mostly shooters).

What I like to do is to look at the Lenght/price ratio of a game to see how much it was worth.

if it's less than 3 € I feel that it was ok. (so 20h of gameplay for 60€) ... then of course if it's not fun, i still feel cheated ^^. (also why I dislike buying games full price this gen... most are not fun enough).

I think Cod, any of them because it is just a long running game, exclusive wise i would prob say gears 1 or 2, the multiplayer factor as well. If you are talking single, probably Bioshock or Lost Odyssey. It depends what games you like lol

Tales of Vesperia.