I'm working on a faithful ROTT port to GZDoom and Zandronum to as best as the engines can handle. Already got most actors coded in, got a WIP map conversion script and all assets are reimported from darkwar.wad (need to write a script for that though). It's all currently private on Dropbox, so there's no repo for it right now. Some methods are unorthodox to conform to vanilla methods, like:

• Using special path arrows for moving objects.
• Have moving walls follow an actor to try and keep them in sync as GZDoom and Zandronum can't have solid polyobjects that pass through unkillable blocking actors.
• Alternatively but WIP, moving walls will be done via fixed paths in ACS. This may cause some incorrect behaviour with some custom maps that require some walls colliding for puzzles.
• Catwalks and walls with variable heights (catwalk marker) use 3d floors instead of 3d midtext.

Some things I still need to figure out is:

• Make the enemies not shoot if their LOS is blocked by windows and other actors (may have a non damaging hitscan checker).
• Make the GAD's more reliable. They currently use Warp to attach players to them and it works well, however faster speeds may make players fall off.
• Have enemies move using velocities rather than A_Chase to help them use jump pads more reliably.
• Make Split Missile behave like in vanilla ROTT.
• Make Crushers work properly and try and squish the player view height.
• Make pit traps work that also lowers the player view height.
• Make the dog weapon cause the player to jump when pressing use.
• Have variable pitches for the charge up of the dog howl.
• Completely remove player Pain states but allow their sound to still play. (Currently pain keeps resetting their animations)
• Add the intro and slideshow screens.
• Make it so the player can only hold one large weapon.
• Shrooms and Elasto powerdowns.

Other WIP things:

• Have the map conversion script add timed events, fog, line properties like switches and make elevators work. Also spread out some coop starts from the single player starting point.
• Put the exported TEXTMAP into a WAD file.
• All bosses.
• Multiplayer stuff like Collector items and other gamemodes.
• Finishing the reworked HUD.
• Score system, which is also scoreboard friendly in Zandronum.
• Redo the font system myself rather than using Return of the Triad's fonts.
• Make GZDoom not treat the mod as Doom

Noticeable differences:

• Excalibat's offsets are adjusted for widescreen.
• Excalibat can be swung from the left side right after a right side swing (no gameplay change, just visual)
• HUD reworked from vanilla. Mostly due to chat area messages overlapping the top bar, and also it was ugly overall.
• Lives system has been removed. Instead, 1-up and 3-up items give full or super health respectively. This however may change for Zandronum's Survival hamemode.
• Max life is increaseable by 1 when collecting 100 life points.
• Knife is now useable as a weapon in slot 1.
• Pistol changed to the Dual Pistols right hand sprite.
• Dual Pistols use the regular Pistol firing sound.
• Getting Dual Pistols will remove the single pistol.
• Single pistol slot changed to 2.
• Female and Darker (for Doug Wendt) skin tones for the knife and god hand.
• Various dog colours based on gender or race (Male: Brown, Female: White, Doug Wendt: Black).
• Dynamic Lights.
• GLDEFS based brightmaps.
• All HuntBegin, Darkwar and most additional levels will be added as all in one. HuntBegin starts as E0Ax to not conflict with Darkwar's maps, All non single/coop maps will use a different naming style.

Planned differences:

• Smoother muzzle flash animations.
• Add some various gameplay options, like what the ROTT 2012 mod changes, and the ROTT 2013 game changes.
• Strife style brightmaps rather than using GLDEFS textures. I may be able to do this easily by fixing the COLORMAP to work with ZDoom properly.
• Complete support for Return of the Triad's maps.
• Support for playing through Doom/Heretic/Hexen maps using ROTT actors (if loaded with respective IWAD and patch).
• Support for playing through ROTT maps using Doom/Heretic/Hexen actors (if loaded with respective IWAD and patch).