>>105954532
Both. When I first started I was just looking at the asm (with debug symbols). I tried Ghidra briefly but it's kinda junk for DOS stuff. I managed to figure out their resource mangling algorithm and how all the graphics resources and track files worked using just the asm and a lot of trial and error plus some help from other less technical fans of the game. Also had a beta version of the game where the resources were not mangled. Wrote a pretty good track editor and resource converter that way: https://github.com/Zizin13/RollerTrackEditor

Now I am using IDA which has a decompiler specifically for Watcom, the compiler they used to make the game. I have gotten pretty good at using it and am making very good progress. I think I will have the entire thing decompiled in a few months. https://github.com/Zizin13/ROLLER

Finding a released exe where the debug symbols were not stripped is what made it all seem possible.