Whoops, looks like I uploaded a version where I'd turned enemies off for debugging and forgot to turn them back on. I haven't actively worked on this in a while but still thinking about wrapping it up at some point
The default window size is 1024x1024, so if your monitors resolution is lower than that it might mess things up. I'm going to try making it so it automatically detects your resolution to see if that fixes the problem.
*edit* see if the problem persists with the latest version