http://www.tremorgames.com

Basically, tremorgames is a site where you can do surveys, tasks, watch videos and play achievement games to earn TREMOR coins, with tremor coins you can exchange them with steam games, steam wallets, TF2 items and everything you want.

This site is actually legit, and I won from there four games, I made to giveaways in here.

so, steps:

1- Register here: http://www.tremorgames.com
2- Start playing achievement games, and do tasks, watch videos etc.
3- You will get TREMOR COINS(with tremor coins you can get free steam games)
4- Exchange your coins with items.

Evidence that it's a legit site and I've won four games:

http://i.imgur.com/vihJQwK.png

Happy Gaming!