What is the best game you have ever bought?

ROFL, do you buy games?
According to hours spent I can say that Counter Strike : Global Offensive was my best buy xP

CS:GO, almost 650 hours :D

I loved Diablo II and the good old Monkey Island games, especially The Curse of Monkey Island! I played those games countless hours and I still love them and could play all day.

man, NOTHING on this earth beat super metroid from snes.
bought psp just to play it whenever i want to.

With over 1700 hours of play recorded (and probably another 300 not recorded) I must say Football Manager 2013,

Tetris DX on the Game Boy Color. Easily the best version of Tetris as far as I'm concerned, purely for enjoyable game play with classic music, no ridiculous mechanics solely for competitive play (T-spin), easy to get into and share with others, and the cartridge is still going without ever having to replace the batteries thus far.

I don't know how many hours I've put into it, but I've yet to go a week without playing it since it's release.

borderlands

The game I most likely spent most time in was Ace Of Spades 0.75(before jagex and BnS). After this would be BF Vietnam. And after it might be Sparky and hutch(not really my favorite, but I spent a year without any internet and game stores to go and buy stuff, so it was the only game I had).

Also Tetris on the phone. Played too much of that blood sucking thing.

Gothic 2

Binding of Isaac

Binding of Isaac + DLC...
I bought it for 0,69 $ and spend 120 hours on it :) .

Final Fantasy IX

maybe already spend about 250 hours on it

Quake + mods and maps:-)

Gonna have to go with Diablo 2 on this question. Not sure the number of hours or if it is near the most for me, BUT I have gone back to it multiple times over the years and still found it enjoyable.

轩辕剑叁外传：天之痕 or 轩辕剑外传：苍之涛.

all fallout games, all deus ex, defense grid, l4d2, hl series, witcher series, diablo 3.

Tales of Eternia and Final Fantasy IX, Fallout 1-2. Games of my childhood. Oh, I also like Tales Of The Abyss.

Tomb Raider is my current fav

Dragon Age Origins.

Witcher 3.

Garry's Mod and Portal 2 :)

Chromehounds.

favorite is frozen synapse; most time is either minecraft or gnomoria

I got into a lot of games but if where talking about the ones purchased from steam I'm gonna have to say Wargame Red Dragon. Never has such an impressive grand RTS run so well on my old computer.