I've noticed that World of Goo is available through Impulse. The game is known to have a proper linux version. I would buy World of Goo through Impulse if your distribution system worked on Linux. I live in a country discriminated by PayPal and can't purchase World of Goo.
Sins of the Solar Empire has 'gold' rating on wine appdb, meaning it works very well when emulated. Another reason for making Linux version of Impulse available.
http://appdb.winehq.org/objectManager.php?sClass=version&iId=12495
I understand that declaring official support for another operating system like Linux is a commitment and responsibility you may not want until it's apparent that investing in linux games pay off. But you could employ a 'stealthy' approach, like Blizzard allegedly does. Blizzard games, most notably WOW, Warcraft3, Starcraft, Diablo all work very well in wine (gold rating). Blizzard allegedly had (has?) an internal linux version of Warcraft3, which is used to make sure the game is compatible with wine. As stated by someone else, linux users are used to helping themselves and spread tips on how to get these games running, even though there's no official support. The end result is that Blizzard doesn't have to commit to any official support, and more technically-minded and determined players are able to get Blizzard games running on Linux. This means extra customers.
I would be happy with official release of Steam for Linux - because any new Linux games are good. But I would be even happier if it was Impulse, not Steam. I'm allergic to DRM.
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To Stardock employees:
I must say I'm pleasantly surprised by your activity in this thread, your rational stance and providing straightforward responses and explainations. Many game developers simply ignore 'Linux threads' and don't even deign to repply. This gives me hope that eventually you will support Linux as well - once it reaches critical mass, as we all know it will. It's good to know you're not against Linux on principle.