Kingdom Hearts 2 was pretty easy from I remember, a fairly long game but very easy neither the less. Also I not sure if it really counts, but you can't really lose when playing Heavy Rain all that happens is that the storyline gets altered, so I guess for that fact you could consider it easy. I guess I could also mention The Bouncer(one of the first PS2 games) I beat the game in like a hour and a half on the first play through, and the second time onwards I would play it I was beating it in roughly 30 minutes.
The Ghostrider for PS2 is easy too, I beat it in about 2 hrs.
[Edited by HonestGamer, 3/21/2010 1:17:37 AM]