I found the Desura versions but I've never used it and don't know what to think of it. Is it reliable?
I do agree entirely with your last sentence though. Why isn't GOG supporting Linux?
OK I do know why: GOG offers a "comprehensive" service by selling games that are guaranteed to work. As of now, people still believe Linux is more problematic than Windows (yeah right... Windows breaks EASILY all the time). Still, they say they need to have a support team for Linux, and they THINK they need a support team for different distributions. Don't they understand what GNU/Linux is? As Torvalds says, Linux is Linux. Actually any POSIX-compliant operating system operates in basically the same way, regardless of kernel design and system calls implementation. There is also a filesystem hierarchy standard. Just stick to that.
What GOG fails to see is that GNU/Linux is what it is today thanks to COMMUNITY support. They could release Linux versions of games initially without any warranty, and people would still support other people and help them run and install these programs, because that is how we work. After a while, someone would maintain a wiki of GOG for Linux and people will find FAQs in case their games, for some strange reason, don't work right out of the box. If GOG wants, at this point they could have their technicians read these wiki's and support Linux games as well.
But for now, seriously, it's not a big deal. Simply make games like Machinarium and Trine available as Linux downloads. I want to redeem my Project Eternity with GOG, but I also want to have it available for Linux.
Facio, Voco, Ferre.
*Do not add extra DRM to your game. Support Linux Gaming!*
PC does not equal Windows. PC games should be available for all major platforms. Utilize standard, cross-platform technologies!