This is a small platformer, cobbled together out of bits and pieces of the small amounts of game dev I've done over the past couple years. I'm using it as a testbed for my GGPO clone, Telegraph, and hope to turn it into some kind of semi-compelling versus game/"platform fighter."
It uses a home-rolled ECS that draws on the APIs of entt and Amethyst, albiet with absolutely none of the performance optimizations. It uses immer for state changes, as its use of copy-on-update and structural sharing should theoretically make it is easy to maintain game state and perform rollbacks for Telegraph (at the cost of a whole lot of GC, I think).