If you want to license a film and make it into a video game you offer a royalty - however, your offer would need to include a guaranteed minimum royalty which is either paid up front or split part on signing, part on approval and part on publication. In short you have to have faith that the product will sell and pay money up front.
This company should have sales projections based on previous products. It would be perfectly reasonable for you to ask what those projections are and also ask for money up front, in the form of a guaranteed royalty. This also helps to minimise non-payment of royalties.
You also need a very good contract that defines what you get, what happens (auditing) if you don't think you are getting what you should and who pays for it.