Gamma adjustment doesn't work

[Bucic]

Bucic, do you have a version from Humble and a Steam copy, or have you added the Humble version to Steam library? It sounds like you have both.

I've used the option to generate a Steam key at HIB website, got the game at Steam and installed via Steam. Steam build and HIB build are not identical apparently. One works without issues and the other does not. Let me also remind that I use neither Compiz nor Kwin. I've tested the case in GNOME's Mutter and LXDE's whatever-their-display-layer-is-called.