We were in Java too, so I could run the jar no problem. Have you looked into jpackage? You can build an executable on any OS you're on. We couldn't get our Mac one figured out but that's how we have a windows and linux executable.
I think the levels were a little big and looking for the stairs in a blank block was unintuitive - figured everything else out but didn't realize there were more until I checked the instructions on the main page. Like the weapon versatility, the name made me think I had to break blocks for new weapons though and I couldn't figure out why I could only find #1, 3, and 4.
Making in Java is ambitious compared to a nice editor like Unity - did you use LibGDX or nothing at all? Congrats on getting something close to a proper game in during the timeframe, really!!