The safest form of compression is a "Repack" (often done by groups like FitGirl or DODI). These act like a zip file: they compress the game for download, but once you install it on your PC, it decompresses back to its original size (still taking up 16GB on your hard drive).
Because it is an older title, even compressed versions run smoothly on modern integrated graphics, requiring only a DirectX 9.0c compatible video card and 2 GB of RAM. Risks and Considerations Resident Evil 6 Pc GameFULL-highly Compressed