The problem is, they all use the same code So, either doesn't work for ANYONE, or it's simply not possible that works only on "some people". I am not sure what is going on honestly, I'll see if I get some other people reporting the issue!
Achievement system doesn't work for me. This is the 2nd time i get the message "Achievement unlocked" (100 aliens killed, king of the arena)), but actually Steam still shows 0 achievements for me! I can provide both screenshot and the last save game before gettng the achievement if of any use for you. Btw I''m playing on Ubuntu 12.04, if that matters.
Ok that's not such a big deal, but just to let you know: I've got another renpy game, Magical Diary, and achievements work. Maybe you hould give your coder a piece of your mind... P.S. Anyway Magical Diary sucks, so I still prefer your games!