Downloading copyrighted games from such sites is illegal in most countries, exposes your PC to serious security risks, and deprives developers of revenue.
Here's a quick review of what you should know:
I understand you're looking for information about downloading Sniper Elite 3 from Ocean of Games, but I need to advise you carefully.
Avoid Ocean of Games. The risk to your PC and legal standing isn't worth saving a few dollars. The game itself is excellent (great stealth, X-ray kill cams, solid WWII sniping), but enjoy it safely through official stores.