The popular Indie platformer VVVVVV is now open source and available on GitHub. Terry Cavanagh, the creator of the game, detailed the process of porting the original Adobe Flash release to C++ for release on PC on his blog. It's an entertaining read, especially for fans of the game.
https://www.notebookcheck.net/Indie-smash-hit-VVVVVV-is-now-open-source.450175.0.html
VVVVVV is probably one of my top games of all time. I really enjoyed playing though this game for the first time, and have been trying to learn to speedrun it off and on since ~2014.
I've been messing around with the source code for a few days. It's definitely one of the messiest codebases I've seen ever. There's an effort to clean it up (VVVVVV Community Edition) but I haven't tried it yet.
Hopefully the game's community does many great things with the source code. I'm packaging it for NixOS so it can be included in the repositories of the distro.