Yeah, a lot of the codebase was like that. Some lone wolf mad genius that occasionally left pieces of pure brilliance behind, but more often than not, just wrote code that was incredibly idiosyncratic and unnecessarily reinvented. Like he'd spend several files making a color gradient visualization system with his own scales, with an enthusiastic but limited understanding of color theory, that ended up producing mostly reasonable but occasionally insane color scales. We spent several days of back and forth discussions with him before understanding what he was actually trying to do (which isn't what his code was actually doing) and then replaced it with a one liner out of a standard visualization/color lib.
The entire codebase was like that. It stood out to me as the work of someone who was very smart but worked alone and never had to work with a team, and never considered what someone trying to retrace his mental process would have to go through. He left zero documentation or comments, built the whole thing in a rush, sold it to another company, and we were the ones hired later to clean up his mess.
Some of it was very good. He was really good at efficiently encoding low level network traffic over packet encodings he invented or heavily modified. Seemed like he would've been a brilliant signals engineer or cryptologist. But having to work with his ordinary business logic code was pretty nightmarish, if interesting from a reverse engineering and psychology point of view.
It's just not how I would ever want to write code meant for mere mortals. But then again, he's a multi millionaire now and I'm a rando nobody living paycheck to paycheck, so I'm in no place to judge lol.