: Most often, these files are malicious. The 12 MB "installer" is actually a Trojan or Spyware designed to compromise your PC, steal data, or enlist your machine into a botnet.

To run the legitimate version of Resident Evil 5 on PC, your system should meet these standards: Resident Evil 5/ Biohazard 5 system requirements

To put it bluntly: it is mathematically impossible to compress 18 GB of complex textures, high-definition audio, and game code down to 12 MB while keeping the game functional. For context, a single high-quality photo from a modern smartphone is often larger than 12 MB.