Zombie Marines eject bullet casings, the MP40 gets more frames, the Chasm Scorpion appears, the Acid Demon sprite has been upscaled and there are more HD textures.
In the final release before the upheaval of version 40, some things have been addressed and updated.
Zombie Marines (the running dudes with assault rifles) now eject bullet casings when they shoot, just like Zombiemen and Chaingunguys.
The MP40 reload state has been expanded with new frames that make it a little more fun to sit through. After all, detail is good! These frames were taken from Wolfenstein X by V0RPAL.
The Chasm Scorpion from, well, Chasm, as adapted by Pandut and Hal9000, has been added as a new monster that gets spawned in Icon of Sin and wherever there's a BossBrain. All these new BossBrain monsters will be making other appearances later, once some new mechanics for that have been introduced. But that's a spoiler for what's coming!
The Acid Demon has been upscaled with frames from Doom 64 CE. Pretty sure it doesn't actually appear in-game, but they made the frames and I found 'em, so...
And, as usual, 10 of Hoover1979's HD textures have made it in.
Also--I switched out the platform looping sound for a sound out of Doom 64 CE for something else entirely. it's a cool. industrial, creepy sound. I had to change it to that, because the other one was from a Quake game. If I can help it, I don't want this to use anything from games made on id tech 2+.