If I had to take a guess, it would be that it probably has something to do with the wild constellation of libraries any given Linux machine could be using, not to mention version of those libraries. Do you build your game to support ALSA, or OSS, or Pulse Audio, or all three? (I'm not a Linux dev so these examples might not be technically right but it's in the spirit of my point.) Do you use the dependencies present on the system or include your own? Does the user have good drivers for their hardware? Do you target OSS or proprietary drivers, or both? Often proprietary drivers have showstopper bugs on Linux that take forever to get fixed, if they ever do.
When your Linux customer complains to you that your game doesn't work on their version of the ATI proprietary driver, what do you tell them? "Sorry, wait till ATI gets off their ass and fixes their driver, otherwise, you can try entering this arcane set of CLI commands to see if it helps, cross your fingers you don't bork your existing driver in the process, and if not here's a refund?"
It's probably just not worth the support headache. After fighting with Linux driver and dependency hell more than once I don't blame them.
Edit: even some of the past bundles have had Linux problems. I think only half of the games in the last bundle would even install on my stock Ubuntu laptop. More than one of the games--the two Shadowgrounds, I think--in an earlier bundle needed some arcane hacks to get sound working. It ain't easy supporting Linux.
If there is one thing the Humble Bundles have proven, however, its that you CAN port your game to Linux and make money. Linux users have traditionally paid more for the bundle, and there are very few good reasons why a game cannot be ported to Linux. So many great games in the Bundle series are available on Linux, so clearly its possible - and clearly there is money to be made.
So its really just a matter of groupthink about "Linux isn't viable" thats the block, here.
When your Linux customer complains to you that your game doesn't work on their version of the ATI proprietary driver, what do you tell them? "Sorry, wait till ATI gets off their ass and fixes their driver, otherwise, you can try entering this arcane set of CLI commands to see if it helps, cross your fingers you don't bork your existing driver in the process, and if not here's a refund?"
It's probably just not worth the support headache. After fighting with Linux driver and dependency hell more than once I don't blame them.
Edit: even some of the past bundles have had Linux problems. I think only half of the games in the last bundle would even install on my stock Ubuntu laptop. More than one of the games--the two Shadowgrounds, I think--in an earlier bundle needed some arcane hacks to get sound working. It ain't easy supporting Linux.