dokapon kingdom for the Wii, Me and my friends had loads of fun playing that game. We ended up playing until four in the morning, which is something we hadn't done since Warcraft III and even then we had played D&D and Halo in the same night, this was just pure from 7pm to 4 am fun with a single game, and we didn't even get close to finishing. (Darkling was a bit of a game ruiner though early in the the game someone got darkling due to them spending all their time playing on red chests to get the best items and leveling their character so when the emerged stronger than everyone and played that whole, all towns are neutral no one else has any equipment and I got that castle you were all fighting for earlier so I come out with more money, much stronger gear and a higher level than all of you guys... Kind of a game ruiner...
I DID break my system loyalty to Sony by buying a DS to play the world ends with you, which is a VERY refreshing game for a system that IMO is far inferior to the PSP, which as a poor person, acts as my MP3 player, my cellphone, my video player, and a tool to browse the internet, not to mention the slightly better than PS2 grade games.
I have considered breaking from my PS3 to the Wii for No more heroes as well which looks amazing, or at least it does on the Japanese version my friend has for the ps3