Which video game have you spent the most time on?

[Fayceless]

WoW.

 

But outside of MMO's, probably Alpha Centauri.  I've played that game since 2001 and spent countless hours on it.  No 4X game has ever quite matched it, IMO.

On Consoles, one of the Super Smash Bros. games.

Handhelds: Pokemon Blue.