Ytterbium

Ytterbium ore generates naturally in the world and drops ytterbium when mined. Crafted items include the ytterbium staff, which is built in the shape of a big stick made from ytterbium. Dropped into fire, the powder catches alight, and it can also go into a compost bin or serve as furnace fuel, so it is both a crafting input and a fire hazard.

Gamma rays form the mod's central mechanic. Ytterbium is their source, and getting hit by them through the staff applies a radiation effect with a range of 6 blocks. The effect sets babies on fire, makes adults glow and damages mobs and players it reaches. Redstone builders get two clock blocks: the analog clock cycles its output from 0 to 15 and increases with each tick, while the binary clock toggles on and off each tick, and gamma rays can be made to use precise clocks.

The mod is published for Fabric only, for 1.21.11, and it runs on the client and the server, so both need it. The code is open source under the MIT License. The project has public source code and an issue tracker. A hex display that shows input signal strength is noted as needing a better texture.