This is a pre-release with 3 episodes, where only the first is considered completed (no maps will be remade in the future). Also only the first one has more difficulties. The 2nd and the third episode are more bland, with bugs confusing puzzles,unbalanced fights and no difficulties.
Zip version, contains .exe that automatically runs it with gzdoom., when it is in gzdooms folder. It can be played on Linux,Mac and Android (Gzdoom android, that is still in beta). Simply run gzdoom -file dtsotb7pree1f.wad and it will auto-load all pk3 files. Then exec dtsot_default.cfg to gain a full expirience.