Thank you for your comment! The game is indeed more or less coded from scratch. More or less because it does use some libraries to take care of low level graphics and audio stuff.
It's a bit of a weird game in terms of genre and gameplay, so no framework really felt like a really good match for it. That's more or less why it ended up like this. If I had made a pure VN, no doubt I'd have gone for Ren'Py.
I'm afraid that the game probably won't run on FreeBSD because one of the libraries it uses (LibGDX) apparently doesn't support it. That's a bummer since the game code itself should work if it weren't for that.
Thank you for your interest and the kind words! I hope you enjoy the game.