Getting a proper FPV simulator on a Mac without paying for one is a real gap. Most sims with detailed flight physics run on Windows, and Mac pilots have been stuck with slim pickings. The maker wanted a free option with detailed physics, and instead of waiting around, they built one on top of an open reimplementation of a Grand Theft Auto game.
The project is a modification of reVC for Mac, and it turns that game into an FPV simulator where you can fly drones through a Vice City setting. Under the hood it runs the SimITL engine, which the maker compiled for Mac themselves. That choice of base engine seems like a smart starting point for flight behaviour, in my view, since it is already aimed at this kind of flying.
What stands out to me is the series this belongs to. This is episode 4, and earlier work includes integrating libsm64 into Super Mario 64 to create an FPV version of that game as well. The maker also used Claude Code to help modify the games, which is an interesting workflow for this kind of tinkering.
It is not all polished. There was a bug where the libfpv overlay got applied repeatedly with a fisheye effect stacking on top. On the open questions side, the maker has not decided whether this will be ported to the regular PC version of Vice City, and there is no clear path yet for an iOS version. There is also a plan to upload the web mod rather than host it directly, apparently to keep legal risk down, which I think is a sensible precaution.