Throughout this week and next, Gamasutra is presenting a year-end retrospective, discussing notable games, events, developers, and industry figures of 2007. This time, we give careful consideration to the game developers who have done the most to advance the art and science of gaming worldwide in 2007. This chart may have some overlap with the 'best games' chart coming later this week, of course. But we're picking top developers for their attention to detail, grit, and willingness to push the envelope, not necessarily simply on the finished product's overall quality - though all of this year's Top 5 Developers have worked on spectacular titles. The developers picked are the editor's choice, and for every one settled on, there are many others - from Infinity Ward through Insomniac to Nintendo EAD Tokyo and Naughty Dog - that we also greatly appreciate. Here's our line-up: 5. BioWare (Mass Effect) While it may verge on the over-complex in some gameplay mechanics, BioWare's masterful Mass Effect feels like a genuine space opera. It has whirling emotions and a genuine story arc - so genuine, in fact, that you start to realize how basic the story in many other games is. In addition, the character customization using Unreal Engine 3 made players even more acutely aware of their immersion in the action. And with fruits from Dragon Age to the 'mysterious' MMO still due under new taskmaster Electronic Arts, one can't help but think that the golden age of BioWare's story-driven epics has only just begun. 4. Bungie (Halo 3) Some cynics might say that Bungie not being #1 on this list means that they've failed, given the stratospheric expectations for Halo 3. Well, hardly - the single-player game was still rapturously received. But where the newly independent developer scored, for me, was in the multiplayer immersiveness. With social networks ravenously engulfing the rest of electronic media, the incredibly complex stat tracking and multimedia upload capabilities of Halo 3's online modes make for a world in which tracking and replaying your interactions mean as much as the gameplay itself. Games still have a long way to go on their path to social media, and Bungie blazed the trail in 2007, while quietly setting up as independent of Microsoft. 3. 2K Boston/Australia (BioShock) Of course, the team we'd all love to call Irrational always knew that BioShock was a critical darling, but to break out to commercial success - and with such a relatively odd, highbrow setting - was a surprise to many. But Ken Levine's team took their time and presented a carefully structured game world where morals mattered, dynamic and emergent gameplay was rife, and Daddies were Big. It may already be a 'franchise', but as an original piece of art, BioShock rocks, and 2K Boston should be proud of the iteration and perseverance in birthing it. [UPDATE: Jay Kyburz notes in comments that 2K Australia should also be honored for its role in co-developing the game. Agreed - now they are.] 2. Harmonix (Rock Band/Phase) When a developer thrives after its signature franchise has been taken away from them - that's when you know they're destined for greatness. And Boston's Harmonix did just that with Rock Band, possibly the best multiplayer game of all time - while sneaking in officially overlooked iPod breakthrough title Phase along the way. It's not just the pure technical execution, either. In the innards of Rock Band, you can feel the love of rock music screaming out to be heard from the developer, something that's widely agreed to be somewhat lacking in Neversoft's still competent Guitar Hero III. It's a game that makes you feel - and most often, that feeling is great. Bravo, Harmonix. 1. Valve Software (The Orange Box) Sure, plenty of other developers shipped a great game this year. But, let's face it, how many of those developers shipped three great titles all in one year, while simultaneously owning and operating a major PC game distribution portal? Thanks to the puzzle humor genius of Portal, the beautifully art-directed multiplayer smartness of Team Fortress 2, and the pitch-perfect storytelling and humanistic drama of Half-Life 2: Episode 2, all packaged up neatly in The Orange Box, Valve deserves Gamasutra's award for the 2007 Developer Of The Year. (Mind you, expect a Halley's Comet-style gap until they next release this many titles in 12 months!) [Do you agree or disagree with these picks? Feel free to sign on and comment below. We'll pick the best Gamasutra reader comments on each list for our final retrospective, to debut late this week. Already-posted lists include Top 5 Downloadable Games, Top 5 Most Affecting Characters, and Top 5 Overlooked Games, as well as Top 5 Trends.]