Well, Cardfighter is very fun, but the most addictive game to play is Cardfighters Clash, hands down.
But the FUNNEST "game" in my opinion would be, Cat Walk, from Match of the Millenium. I swear, I love these rhythm games, they are so addictive!! You can't put them down!! Anyways...
Jordan>
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~ "They told me to shoot straight,
don't pull the trigger, squeeze.
That way its sure to kill,
a kill is what you want,
a kill is why we breed"
- NoFX, The Decline