I'm pretty sure the biggest influential games of the past few years have all been by Nintendo ONLY.
When I mean influential I mean INFLUENTIAL.
These games are in millions upon millions of peoples' hands, not only shaping the way the hardware "races" have played out, but also spawned an influx of similar gameplay styles in numerous other games.
These games, of course, are Brain Age, Nintendogs, Wii Sports, and to lesser extents Wii Fit and Wii Play.
Little Big Planet is influential? Spore? Bullshit. They're ambitious and AAA, but they released one fucking month ago. Where are the huge sales? Where are the clones? We've seen Ubi-Soft capitalize on the Nintendogs craze with all of their AnimalZ that they pump out. We've seen numerous games and even knock-off books release after Brain Age became massively successful. Hell, I don't think we'd see stuff like Flash Focus, Picross DS, or numerous handheld Sudoku games without the franchise's success. And I don't even need to talk about Wii Sports. It almost single-handedly has given Wii the type of games that hardcore scorn and everybody else adore, probably leading to the small budget/few mini-games from Carnival Games to Big Beach Sports to Deca Sports, and even more.
Influential is what GTA was, or Halo.