A limbo server is a fallback server able to handle a massive amount of simultaneous connections. The player spawns into the void then waits here. It can be used to keep players connected to a network after a lobby crashed or as an afk server.
See TyphoonCore's protocol support
TyphoonLimbo is able to load TyphoonDep protocol-map modules to add a partial snapshots support.
All json files are loaded from the "modules" folder in the same directory as the TyphoonLimbo binary.
You can generate a protocol-map module with the fetcher. Just pick the "page" link of your wanted version on wiki.vg as argument of the fecther and the magic will happen.
git clone https://github.com/TyphoonMC/TyphoonLimbo.git
cd TyphoonLimbo
go build
./TyphoonLimbo