So. Why there is no linux installer?

Game is linux capable on Steam.

b-cuz linux port is in abandonware state, as far as I know. No idea if its still behind windows version like it used to be, but it still should miss some core features, they've promised long time ago (windowed mode, for example). And the last time, I've asked developer regarding that, their answer was something like "linux port was a freetime project of one dude and now he is busy doing different things, so no updates for you"

Well. That make me sad.
That would be a great game for linux.