Tomos, have you thought about using Offerwalls?
For example this site : http://bitgames.io/
using 12 of them and it benefits the site owner and the players.
Easily I am making more then 50000 a day there. Hope soon to make the same here.

And this one here : https://www.coinbrawl.com
gives the players 1 mil satoshi every day for the last year .And he has only 2 banners on the page and only 70 active players.
He is using Google ads. I know it is difficult to get them. But Offerwals I think are good option.