What fan-made games have impressed you the most?

I've always enjoyed seeing what gaming communities can create when they're passionate about a game. Some fan projects end up adding new mechanics, stories, or challenges that make the original feel fresh again.

Recently, I spent some time trying PVZ Fusion, which is a fan-made Plants vs. Zombies project with a lot of creative ideas. While looking for guides and update information, I came across this website, which helped me understand some of the newer features. It made me realize how much effort fans put into keeping these projects alive.

I'm curious what other fan-made games or community projects you've enjoyed over the years. They don't have to be related to Plants vs. Zombies or tabletop games—any genre is welcome.

Do you have a favorite fan project that you think deserves more attention? I'd love to discover something new.