I have used share-it as a payment gateway to resell web hosting.
Unfortunately I didn't make a single sale

share-it is mostly aimed at selling software and other digital goods. You can also sell physical goods.
Of course they will not allow gambling or porn, but I am pretty sure they allow game microtransactions.
cons:
The web interface to configure your online shop is very hard to use.
Generating the buy button link is also a challenge.
pros:
Very good support. Personal reply to all my emails in less than 24 hours.
Very low royalty. I don't know how much it is now, but at the time the percentage they kept was lower than paypal.