...what's the incentive to buy STEEM for players ?
Players don’t need to buy anything. The games are 100% free to play. All you need to do is sign up, start playing, and earn some crypto. No tricks, no gimmicks, no ponzi scamming.
How do you sustain the site ?
With servers and databases that we pay for.
Where do you get the STEEM to divide?
From a variety of sources, as mentioned in the post. Also from my witness rewards and post rewards from official BROSGN posts.
If it doesn't require my steemkeys...
It does not. Just sign up with an e-mail address and create your own password.