CSGO Double

CSGO Double is basically identical to CSGO Polygon. They are both roulette type of games for gambling your CS:GO skins. Currently, the referral program for CSGO Double is down at the moment.

Basically, the best way to play these roulette type games is the Martingale System. 

Don't forget that you can send coins to other people so if you have friends on the site, they are able to send you some of their coins.

Link : http://www.csgodouble.com/

CSGO Polygon

CSGO Polygon is similar to CSGO Empire. The website itself is basically roulette.

Sign into steam and click on free coins tab.
Enter the following code to receive free coins : PROFITS

Link : http://csgopolygon.com/#