Duels is a Minecraft Spigot plugin which allows you to duel other players in arenas. I tried to make it in a very modular way, so I could add new features and maintain the code very easily.
https://www.youtube.com/watch?v=MC4dWEnsMAI
This is something I have made over 2 years ago, and is defiantly not my proudest work, but still something I enjoyed making.