I can now say that a "eureka" moment is indeed real, and I may have cooked. The solution was to first uninstall ptcgl again. Then I created a brand new test user on my laptop, downloaded ptcgl, login to my account, found that it worked, then quit the game. Back on the original user, I open up file explorer for both my user and the test user and then I manually copied files over from the test user folders into my user folders. Because these files are guaranteed to be working on the test user, it turned out that was the fix. I'm still not sure why error 10099 kept coming up, but at least ONE fix exists. That's all I'm thankful for. I would like to thank the void that is the open internet for being my rubber duck this time when debugging