Rise of the Triad: Ludicrous Edition makes use of a somewhat modified format possibly meant for The HUNT Continues and Steam Workshop. It contains data for each level's author and what not but what if you want to play it on the original game engine? Well it wasn't possible until sometime later because a programmer by the name of 'erysdren' developed a program that can convert .RTLX/.RTCX files to it's original format.
1. Why convert to .RTL/.RTC?
The main reasons would likely depend on your purpose. Are you wanting to make a vanilla-compatible mapset for ROTT? Then you need to keep some things in mind which we'll get to below. But as for COMM-BAT levels and at the time of writing this, you cannot play custom content from the Steam Workshop in multiplayer. This issue played a role in the original Dakkijam becoming a precursor addon following frustrations with how Nightdive is neglecting their remaster.
Luckily you can still load custom content regardless thanks to this command-line, '-filertc' which should be able to load custom COMM-BAT sets for more variety of maps to play with.
1.1 There are some caveats!
While this allows your maps to load in the original game and allow custom content to work in Multiplayer, you need to know that: Each player needs to use this command-line and the lobby must be private! Otherwise it's going to cause confusion to some playing on public lobbies by crashing their game. Now this is not the only caveat to consider but the author names for each map is lost.
If you are trying to backport your levels to original ROTT, you need to be careful not to use the exclusive content such as beta walls and Alt.Upper Textures specifically for ROTT:LE.
2. The Converter
You will need to download the converter here. After it is done downloading, you can extract it anywhere in your computer. Now keep in mind that you will need to use a terminal/command prompt to use this tool. For Windows users, press WinKey + R and type in the prompt : cmd.exe to run the command prompt.
Tell the prompt to go to the
directory that the converter is stored, type in the following :
'cd c:\folder' without quotes.
Like I said, it can be in any folder. You could also copy and paste the path into the terminal/command prompt by pressing CTRL+INS.
To use the converter, make sure your work is in the same place as the converter itself (make sure to backup your copy!) and type in the following: rtlx2rtl.x86.exe filename.rtlx
If you want, you can just simply drag and drop the mapset into the converter and it'll do the job just fine.
3. Closing Thoughts
Now your mapset should work in Ludicrous Edition regardless of format. That was how Dakkijam: The Precursor was playtested and released. A shame that Nightdive hasn't been updating the game to address some of the issues it has but it'll do until then.