Thanks to a request by cxxruptdream I added an option to select whichever resolution you prefer in the menu (open menu with M key). The game will start in your native resolution by default, but once you've selected a new resolution, it will keep that preference. 

This game is fun to work on... I'm going to be adding a few things soon. 

Come join the discord if you have a feature request or idea. Cheers. 

-cfinger