I play mw2 in steam, I dont know about the other mw2 versions like repz, iw4, alteriw, etc.
are they mods? cracked version?
what are they?
They are mainly just free versions of the game. (For players who got banned or can't buy the game.)
You also get DLC content for free aswell, and they've also added some modding support on some of them, allowing player made gametypes and much more.
It's sort of the same as MW2 Steam just with more options and possibilities