After Fifteen

Each player works through a three-phase cycle on their own clock. During the phase the surface is contaminated, and the radiation a player accumulates depends on altitude: above 64 blocks the rate is 2.0 and counts as the most dangerous band, between 51 and 64 blocks it is the dangerous band, and below 50 blocks a safe zone applies. As the radiation level rises, the effects worsen, and when it drops to zero the player experiences two hours of hallucinations.

The cycle runs on timers set to 7, 21 or 28 days, which add a layer of difficulty progression and can stretch the radiation over the whole surface for a long time, disrupting surface-level building. Protection time and radiation time are set per dimension, and values can be changed in-game through commands or the config file. A global command and a development option that uses a nickname are also included.

Atmosphere is added through fake mob sounds such as zombies, skeletons and creepers, explosion sounds, item pickup and drop sounds, messages from unknown players in chat, and occasional Herobrine sightings. The mod is published for Forge only, for 1.20.1, and runs on client and server, so the server and every player need it.