Let's inaugurate this forum!
https://github.com/AleffCorrea/PCE-XE1AP-ANALOGI did not find anything on the web about the XE-1AP/XE-1AJ and how to program into games, and I really wanted to try something with it. Coincidentally I ended up stumbling on some very suspicious code dicking around $1000 during a disassembly of OutRun I'm making (to understand how they calculate curves in their game)... of course that was the Analog mode support driver. I basically went over it until I understood it, alongside Raphael Assenat's hints about what it was doing, commented the driver and made a .txt explaining how the damn thing works.
I'm working with the Mednafen source code to make this more accessible, so check this thread later for it!