You can find the game on its Official Steam Page , which provides the most stable version and automatic updates.
The trade-off for a smaller download is a significantly longer installation process, as your computer must decompress the data back to its original size to play. You can find the game on its Official
Files are encoded and packed using complex encryption algorithms, sometimes reducing a 60GB game to 30GB for the initial download. You can find the game on its Official
Players have reported issues with optimization, including occasional stutters even on decent hardware. Understanding "Highly Compressed" Downloads You can find the game on its Official