During seasonal sales, the Steam Store and GOG frequently drop the price by 75–80%. The Collection: The Batman: Arkham Collection
Launch the game from the desktop shortcut and dive into the shadows of Gotham. Performance Tips for Low-End PCs
Here is what you actually download 80% of the time:
Note that because the files are so tightly packed, the installation process usually takes longer as your CPU works to decompress the data.
Never run an installer from a website you do not completely trust.