Its a freeware version of CS 1.6 game which was modified some time ago by TPB website creators and published in TPB website.
TPB (ThePirateBay) is one of hugest torrent download websites.
If you want to download CS 1.6 TPB directly or as torrent file just click one of two mentioned buttons which is below this text and game screen-shots.
Usefull links - Official ThePirateBay website, Official uTorrent website.