Well this is a shame but in many ways to be expected. Take-Two Interactive Software, the parent company of Rockstar Games, has filed a lawsuit against the developers of the reverse-engineered GTA III and Vice City code.
This is a bit of an ongoing saga, as Take-Two first got the GitHub repositories taken down, which were later restored when the developer of a fork submitted a counter-notice which wasn't argued so they all went back up. The repositories are still live on GitHub right now. The notice mentions this with Take-Two saying the counter notices were "were made in bad faith, and knowingly and deliberately misrepresented to GitHub the contents".
Plenty more is argued as well of course. In the notice it complains how the code now runs on platforms it was never released for where the "Defendants have sought to exploit a potential market that belongs exclusively to Take-Two", it argues against new cheats enabled in the source code which "are strictly prohibited under Take-Two’s terms of service". It goes further, complaining about modding which Take-Two say "encouraging users to further infringe the original Games and to violate their agreements with Take-Two that prohibit such activities".
As a result of the code being public, Take-Two are claiming it the "Defendants have caused and continue to cause irreparable harm".
Take-Two are looking to get damages paid which as of yet "are not currently ascertainable", so they want it to be worked out. On top of that they want the "maximum statutory damages of $150,000 for each work infringed" and they also want their "attorneys’ fees and full costs" paid as well.
The point about cheats is a funny one. Single-player games from the early 2000s have cheats added in? Extra modding too? Oh no, how completely terrible for people to further enjoy them.
Why was this lawsuit coming to be expected? Well, reverse-engineered code tends to be a grey area with it often being against the law, and code from leaks is a big no for all sorts of obvious legal reasons. That said, the source code did require people to actually buy the games for the data, so Take-Two would have still be getting revenue thanks to it.
Sadly though, like most major publishers, they shy away from any sort of open source. In this case, Take-Two and Rockstar are reportedly doing a big GTA Remastered Trilogy so moving to fully protect their code was obvious.