"Cracked" is typically for a game where its executable file (the file you click to run the game) has been altered to allow it to play (initially without the need for a disk) without an online connection.
For Big Brother, it was to get around the online connection, which was eventually dropped, but also to allow the game to be played with mods/cheat mods.
"Skunked" is a "local term" meaning it's a smaller overall size, in this case by reducing the resolution/quality of the pictures in the game, making for a smaller download (and storage) size.
The term itself was appropriately coined by the forum member Pepe Le Pew, who went through the time and effort to make the downloaded package smaller than just better compression of the compressed archive. Since that's the name of the Looney Tunes character who is a highly amorous skunk, it was "skunked" to make it smaller.