We have just announced the start of "The Descent", which is a fun little collaborative Unreal single player mapping event taking place from now until 1st January 2021 over at UnrealSP.org.
The idea is that everybody makes a small map "segment" (play area of 4096^3) and then at the end all of the submissions are organised into a somewhat coherent storyline complemented by beginning and ending maps built by the "curator" (me

While the final compiled pack will be for Unreal 227, we highly encourage people of all platforms to join in - so long as you don't use anything exclusive to UT (Botpack.u) it will all be fine!
Check out the thread including the full rules, storyline and more over here:
The Descent: An UnrealSP Collaborative Adventure!
At the end of the day we just want to get creative and have some fun

Cheers,
~SZ