This is an excellent game. I love it. Very fun to play. Very polished too; it's kind of unbelievable you did this in two days. Did you also compose the music yourself? If yes WOW.
Though I must say I prefer windowed games over full-screens... Sometimes full-screen gets interrupted so easily. Also the browser version doesn't work for me (Firefox) :(
Sorry to hear that browser version didn't work for you (I didn't know that it wouldn't work on Firefox so thanks for bringing that to my attention). As for the music, i didn't make the music as my talents lie in game design and programming and not really in art or music. To solve that I went for a (extremely) simplistic art style and the music is from a guy named Juhani Junkala or Subspace Audio. He makes really good music that is public domain so I use it in a lot of my games. If you want to check him out here's the link: https://opengameart.org/users/subspaceaudio
