A 2d portal game I worked on and off on for a couple years. Really it was attempt four at a 2d portal game. The first three attempts were in Game Maker (which includes enough-portals. It wasn't suited to the complexity or performance requirements so eventually I switched to using C#. I never got close to finishing this game but it's largely responsible for teaching me C# and helping me independently realize that inheritance is bad and pure functions and immutable data are good.
This is where my profile image originated. I picked an icon for Aventyr's exe file to indicate that it's a work in progress. Then for some reason I started using that icon for profile images (when I can be bothered with setting a profile image)