Chunky-Challenge

Each run begins with a challenge start that closes the border around the player's current chunk. Random mobs spawn inside it, and zombies, creepers, witches, skeletons, pigs, cows, sheep and chickens are among the default options. Mobs receive a Glowing effect, so the player can track them through walls. The barrier remains in place until every mob in the arena is killed, after which the next chunk opens and brings the next arena. Endermen and other teleporting mobs are pulled back into the arena, so a player is never stuck behind a closed barrier.

A permanent HUD timer at the top center of the screen tracks elapsed time, the current arena level and the number of mobs still alive. The challenge can be stopped with a command, which ends the run and reopens the world. Commands for start, stop, status and config require operator permission level 2, while the status command works for everyone. Settings are saved automatically and cover whether all mobs or only hostile ones spawn, whether bosses such as the Wither are allowed, how mobs scale with arena level, and whether a chunk is filled completely with one block such as gold, diamond, slime or ice.

The mod is a Fabric build for 1.21.11 and runs on client and server, so the server and every player need it. It is released under the MIT License, but it is not open source. The idea is inspired by the YouTuber BastiGHG.