I was astonished to see that the entire game was one 14,000 line file. In a way it's quite impressive, I think I'd go mad jumping through a file that large, but the author really needs to modularize the code if he hopes to re-use any of it / continue development at a good pace. For comparison my game lanarts is ~4x as much code over ~300 files.
Not taking away from the game, or author, of course! Porting to linux was easy, I'll help the author with that.