Awesome, and apologies for how long it took. We had to take a break from development last year but we're back on it now.
Don’t apologize, codingand gamedev is a hard craft and there is no shame in not overworking oneself. The fact that you got back more than makes up for the inconvenience of waiting, and already puts you far ahead of many game companies from the perspective of a Linux user. :)
Ok, so, no surprize at all here, the game requires OpenGL 3.2 at least. You may want to put this as a minimum requirement.
Works rather well with software rendering on a mobile 1st gen i5 though, apart from occasional hang-ups and fps drops in menu, as well as when rendering shadows or many sprites.
Testing will continue when I get to my actual computer.