Some Free Rockstar games

So I was watching this video about what the best way bully is on pc and the guy directs you to this mod of the game that's meant to add alot of 'classic improvements'. Now in the video he instructs you to delete your your local files on steam and replace them with the mod, which, is fine yeah but reading the mods blog post its on.. it isn't a 'mod' per se, like it is modded yes but it isn't just modded. It's a full build of the game.

What does that mean? basically you don't actually have to own the game on steam to play it. You can just.. download the 'mod' and play it lmao

here's the link(s) if anyones interested (they also have a similar 'mod' for manhunt)