Hey there, we’re very glad you figured it out! In truth, none of us are native Linux developers, so it’s hard to test for Linux use on our own– all we know is that Gamemaker’s linux export is designed for Ubuntu (which you’re on, which leads me to believe there are other problems!).
We’ll need to get more linux users to help us optimize the experience and iron out issues like this.
We hope you enjoy the game regardless! -Polar