Endless Ocean 2 - 199 hours
I tend to buy games late though, so while EO2 would still be my most played game this year, most of the other games I played a lot of were released before 2010 and I bought them this year, or I am still playing them from ages ago (Battalion Wars II and Mario Kart Wii)
as such, next in line:
Metroid Prime Trilogy - 90 hours
F1 2010 - 83 hours
then a non Wii game - Trackmania Nations Forever -59 hours
The Godfather: Blackhand Edition - 38 hours
Phoenix Wright: Justice For All - 30.5 hours
Red Steel 2 - 29 hours (and counting)
I can't be bothered to list the rest, but I have spent some time on 7 other Wii games (none release in 2010), 6 other WiiWare games (4 released in 2010) about an hour on the recent Wiiware demos and 12 minutes on SMB:Lost Levels for the Virtual Console.
I also bought GTA:San Andreas cheap for PC, and played some Vice City too... i'd have to put the games in to see how much i played exactly, but I estimate about 15 hours of VC, and 40 for San Andreas.
And finally I downloaded portal when it became free on Steam, which I have spent 7 hours on.
In total this year so far about 520 hours on Wii games (only 2 of which released this year EO2 and RS2) about 90 hours on WiiWare (5 of those games releasing this year) and about 125 on PC games (none release this year) ignoring online flash games.
