Multi Theft Auto VS TORCS

If the code is compiled, you'd have to pull a few more tricks. But to be fair that is also an issue even if your code is not source available - people can (and do) decompile closed-source programs and hack on them. My personal favourite of that is https://multitheftauto.com/ where the community reverse engineered GTA San Andreas to add multiplayer. Source: 12 months ago

I'm well into the nostalgia of games from my youth at the moment, so I've been playing Multi Theft Auto: San Andreas - the modded GTA SA with online multiplayer (https://multitheftauto.com/). Source: over 2 years ago

You can download it from here; https://sourceforge.net/projects/torcs/. Source: over 1 year ago

TORCS: It is the pioneer simulator of free software. With a development with more than 20 years, and with several names behind it (RCS, ORCS and finally TORCS), in this game we can play single races, championships, endurance ... With a wide variety of cars and circuits in a completely 3D environment. The game can be controlled with a wide variety of peripherals such as gamepads, steering wheels and of course... Source: about 2 years ago

For those who don't know, Speed Dreams is a multiplatform (Linux, Mac, Windows...) Open Source racing simulator that started 13 years ago as a fork of the (also free) TORCS, surpassing it in all aspects, especially in physics and visual simulation. Source: almost 3 years ago