Ensure your Windows Page File is set to "System Managed" to prevent crashes during the heavy decompression process.
This reduces the original 6 GB to roughly 2.5 GB without piracy.
While "highly compressed" versions are popular for saving data, be cautious of files that seem impossibly small (e.g., a 10GB game compressed to 50MB). These are often or contain Lossy vs. Lossless:
Right-click the setup file to ensure it has permission to write to your Program Files.
The highly compressed version of Serious Sam 3: BFE for PC typically includes: