UDK is free until you start selling. Then you pay $100 up front and then 25% of profits after the first $50,000 in profits. A full Unreal 3 liscense costs a lot of money up front but gives access to everything.
You'd have to discuss the UE3 licensing with them. I'd imagine they can figure out an agreement for a lower-cost UE3 license with an agreement for royalties.
like Angel_Mapper said no licensee will tell you that, in their contract they are not allowed to disclose any information you get contracts that needs to be signed, contact epic it's the only way to answer your question
Comment