GTA, IGI, HITMAN, WOLFENSITINE CASTELMANIA , MAXPANE are some of my favorite.
I have downloaded all these games for absolutely free, I just did some research and some of the cool websites that provide us with the direct link to download the games.
I have found the complete list of those.
You can visit here to find the complete list of such websites that allow you to download the games for free and the best part is that they are completely legal ones.
https://toptecheasy.com/best-websites-download-pc-games-free/