It's a Fork of a Doom Editor!
TSoSLADaE is a modern editor for Doom-engine based games and source ports, fine-tuned to support more of the SRB2 community.
It essentially has the same features as regular SLADE, with more changes made to help SRB2 members, like me, and maybe even you, in your modding journey.
See the COMPILE.md file for details on how to Compile TSoSLADaE on different platforms.
If you wish to help support SLADE development, feel free to make a small donation to the vanilla SLADE developer, sirjuddington.