Created by two German collaborators, Oh My Git! is an open source prototype game that introduces players to Git in an interesting way.
Players progress through a series of 'challenges' that are actually Git tasks done on a real Git repository. The internal structure of the repository is updated visually, in real-time with each command.
For Git newbies, there is the option to use cards to apply different commands. Dragging the cards over the tree to 'drop' it on a node turns out to be a pretty satisfying experience. However, there's also the option to type commands directly into the terminal if that's your thing.
Some of the levels will teach operations that are incredibly useful for anybody using Git regularly. Things like undoing a bad commit, or how your local actions will effect remote repositories. It's a great way to get introduced to Git or serve as a refresher for experienced users.
For those that may want to use it as a teaching tool, Oh My Git! is made with Godot and entirely open source. So, it would be possible to add more challenges for specific training purposes.