Games that were so big, they spawned many more games for the genre

[d21lewis]

Wii Sports: Spawned an army of motion controlled knockoffs

Nintendogs: The reason why Petz, Catz, Babyz, etc. exist.

Brain Age: Go to your local games store and count how many Sodoku /learning coach/ language titles are on shelves

Mario Party: Crash Bash, Sonic Shuffle, Mario Party 2-8, etc......