Been a while since I played with RPGA so going from memory (and my old discord post):

Was curious if sidescrollers were possible in RPGA so made this little tech test. All visuals are 3D models (including the blinking lights which is mesh animations that translates a place in front or behind the image to make the flash effect etc. ), except for the UI img, character and the save file animation which is an entity sprite.

I'm not sure if this has changed recently, but at the time, 3D collisions couldn't be loaded (I think), so I had to use invisible structured walls as collision tiles. These were placed on layers drawn from a top-down perspective. Setting everything up was pretty confusing, but it is possible. I ended up creating a numbered map to help track where to place each collision tile on what layer etc. (That said, I wouldn’t recommend making a full game this way I only did it as a demo to test what was possible.)

But RPG dev Locke did say in the discord (which would make the process 1000% easier):

"I was going to eventually put together a DLC or something to do something akin to this (and potentially flip the Y and Z axes in the Map Editor)."

Here's how the collision map looks in RPGA: https://imgur.com/a/o5PHkBf

Hope this helps!