Because a lot of gamers want games for free. There are a few sites where you can earn them. Like TremorGames http://www.tremorgames.com/?ref=698096, SteamGifts, Galagiveaways and Playblink.
Now about GameMiners..
After registration, You will have 30 Coals. With them You can partipicate in giveaways for steam games.
Some giveaways cost nothing, some 1 coal etc..
For every hour You will receive 1 coal.
Or You can create own Giveaways (must own game code or gift) and earn more Coal or maybe Gold. For sure You will earn exp to increase Your lvl (more running own giveaways, more invitation codes, more coal per hour etc..)
I wrote about Gold. Yep with Gold You can partipicate on premium Giveaways or buy keys and open earned crates..
Crates obtains Coal, Gold, Name/Status paints and Steam Games
Gold can be purchased or can obtain 1 Gold for every invited person.
So Link is here http://gameminer.net/
(You can register only with invitation code)
heres a invitation code is here:
c364d14b40f75139aa568df4ea69e879
Good Luck in giveaways
