Alright then that confirms my suspicion about changes in RetroPie with Raspbian Stretch.
Sounds good. I recently looked into the RetroPie Sonic robo blast Srb2 script and i was thinking that maybe sonic robo blast 2 which is based on Doom Legacy could provide some info on compiling Doom Legacy for SDL.
As for Doom Legacy the closest thing i came to get it working was building/compiling for X11 window in Raspbian desktop and i could only get the Doom menu to work.
It makes perfect sense to use Doom Legacy source port than ReMooD since it still is actively developed on.