Most likely, it is included in some kind of ThirdPartyNotices.txt that ships with the game. It's actually pretty hard to sneak third party F/OSS under the radar in the company of this size - there's automated code scanners, among other things, and while they can't catch everything, they sure can flag a copy of a public project on GitHub.

What's an example of tool that scans binaries for matches with open source software?

At my previous org, we used black duck for this

https://www.synopsys.com/software-integrity/security-testing...

I don’t think you’ll find one. Most of these operate on the source code and its declared dependencies.

Pretty sure Black Duck does that

Were the flight simulators you can play on that github page originally MIT licensed?

No, but I was just commenting about the license itself. At any rate, this is obviously not a regular thing to begin with.