Heretic stock demo desync

[Wagi]

Since I was a little kid, I was always confused about some of the demos in Heretic. It never really hit me until recently that a couple of the demos supplied with Heretic (at least in Shadow of the Serpent Riders) go out of sync.

The demo on Cesspool almost certainly desyncs. The player suddenly rams into a wall, shoots at it while trying to push through it, and then turns around and stars acting strangely. It even shoots and the ceiling a few times before getting mowed down by Ophidians. Could it be possible that this map was somehow altered after the demo was recorded (the player 1 was moved slightly to the left, or maybe the hallway in front of the player was once wider)? Is there perhaps some older version of Heretic where this demo worked?

The demo on Glacier also seems off, the player dies awfully quick after grabbing the crossbow. Despite being completely swarmed by Sabreclaws, the player casually turns and runs forward --- almost as if the player was moving freely when recording the demo --- and only fires a few times.

[Gez]

Basically, the Raven team did not bother recording new demos with which to update the IWAD when they made changes to the exe.

[Wagi]

So the desyncs are caused by changes to the exe? I'd certainly be interested to know what these changes were. I'm guessing that distributing the original IWAD and exe would be illegal, so is there any way I could see what happened in the original demo (like a video or something)? Or did these demos never work in a released version of Heretic?

[Gez]

You can get the older exes by downloading old shareware versions of Heretic.

[Quasar]

Wagi said:

So the desyncs are caused by changes to the exe? I'd certainly be interested to know what these changes were. I'm guessing that distributing the original IWAD and exe would be illegal, so is there any way I could see what happened in the original demo (like a video or something)? Or did these demos never work in a released version of Heretic?

Amongst other things, I can tell you the behavior of Mace Spots changed completely sometime between 1.0 and 1.3.