Looking around here a bit and noticed a lack of love for Monster Hunter Tri, a game that sold over 600,000 copies in a week in Japan, and boosted the Wii consoles sales from 24k to 98k(units) in that time.

It also has Nintendo's Team Zelda intimidated in terms of in-game graphics and gameplay. With the CEO of Nintendo now breathing down their necks to make sure the next LoZ game on the Wii will be their magnum opus just to compete.

Coming out for the Wii in early 2010 for North America and Europe, it supports full online and offline gameplay with teams of up to four taking on powerful creatures in their environments. Featuring living ecosystems including monsters that need to eat, drink, and other such things necessary for survival, it is easily one of the deepest games on the console to date.

Some basic info on the game

English Announcement Trailer