Not again! I'll try and post different ones now.
Let's try some 1st party greats:
Nintendo R&D 1 - While Miyamoto was setting the world alight with the likes of Donkey Kong, Super Mario Bros and The Legend of Zelda, these guys, under the super legend Gunpei Yokoi were creating a slew of other NES games, including Ice Climber, Kid Icarus and, definitely more important than the rest, Metroid, as well as all of the then groundbreaking Game&Watch games (until Yokoi-san came up with the GameBoy that is). Metroid was indeed a defining game of that generation and with influential impact comparable only to Miyamoto's works. Super Metroid, released 8 years later, was an incredible jump forward and showed an attention to detail that made the environment much more enthralling (much like Shenmue, I guess). And then, in 2003, they do it again, with Warioware, for me, one of the most important games of the decade, with a disarming simplicity yet undeniable charm, paying hommage to gaming's history while at the same time moving it forward. Unlike Metroid tho, it has suffered from an excess of sequels/remakes as it seems to spearhead every new piece of Nintendo hardware these days.
thatgamecompany - Stemming from a new breed of gamedesign AND game designers, this lot of 7 USC graduates have made three excellent games, and I'm sure there is much more to come. Cloud, flOw and flOwer all represent a new age of game design where the concepts are stripped down and the experience is more seamless and contained, while trying to break new grounds on what the concept of what a videogame should be. Entertaining, yet philosophical, this new generation is bound to make an impact, as indie games are on the rise and platforms such as PSN, Wiiware and XBLA are their perfect home.