We think that developer's revenue of 50% is fair. We know that developing a game is as difficult as selling it, and what is more, we split other 50% between us and webmasters who we would like to pay for promoting our service.
But...here's the problem: you don't seem to be *doing* much to justify that 50%. IF you were able to say:
- we run a marketing campaign which reaches 30,000 people every month
- we have full-page advertising in magazines aimed at the youth market (18-24 years old)
- ...etc
then you would be showing how you're doing something to make a 50/50 split fair.
For reference, I've seen people selling the same service where they do a lot more marketing and promotion, and the split is more like 90/10 to the developer (I've also seen a similar service where the split is 40/60 to the developer).
Of course, all this is just my personal take - if you get a stampede of games developers with great games, feel free to come back and show me how wrong I was

. My guess is that you're not going to get much business at the moment.