I saw that advertised on Steam (Windows) the other day, and physically laughed at the $90. Right under that it warned that the software was unfinished and only a small subset of features are available and you will be helping to shape and form the game.
That's pretty obnoxious. (I don't care why)
Still, I'm glad to see that they are making it available for Linux gamers. I won't be participating, moreover, I don't like those kinds of "Real Time Strategy" (genre) games, but I can afford some respect for that.
Really, can no one read? The 90 bucks is for alpha access only, the actual game is $40. The reason that the alpha access is so high is because that is what it was on Kickstarter, and they didn't want people who paid into their kickstarter project to feel ripped off. So, is $90 steep for alpha access? Yes, but if you think of it as an extension to the kickstarter (i.e. you are giving them money because you want to see the game finished, and they give you some bonuses), then its not too bad.
Unfortunately, things are tight for me right now, but as a linux user I'm comfortable with the idea that I may have to pay more to get what I want in the short term.
If more developers are to develop for Linux, then it needs to be consistently shown that their work is profitable. We are currently only that 1-2% operating system, so we need to make a strong showing.
I'd just like to point out that due to the "Australia Tax" that many game publishers feel like sticking Australians with, this is often what we pay for our new release games, Steam or in-store. Blame the publishers for this, it was happening even when our dollar was above parity with the U.S dollar.