The Adventures of Square except now you can load it as a Doom mod and it now works in Zandronum (And K8Vavoom too, though this has not been tested extensively).
That's it, nothing else changed (Besides Shadius losing his/her/it's arms and gaining a teleport ability)
Made a new thread specifically for this one so that all bug reports seen in this version go to me, not the guys at BigBrik games
(But if the bug isn't specific to this version i will forward the bug report to them)
Here's a screenshot to prove that it indeed is Square 2.0 in GZDoom 1.8.6 (Zandronum too)

As usual, click on this red text to download