I shared this previously when I added a Steam version [1] with achievements, music, etc. (the Steam version is also free). Most recently, I added native Linux support to the Steam version, due to feedback from players wanting friend leaderboards on Linux.
The source code is on GitHub [2], in case anyone is curious (but note that it's not Open Source--I'm still deciding how to license it).
Let me know if you enjoy it!
[0] subleq is "subtract, and branch if <= 0"