Selling it as a product has crossed my mind, but it is ok by the CS license. My own skill developement has not crossed my mind yet.
The unreal engine has a whole host of legal issues involved. Also, a 'mod' is considered significantly less than 'game'. (Which would you rather tell your friends? "I helped make the FIRST Video Game." "I helped make the FIRST Unreal Mod.")
I excpect that the diference of dificulty between Unreal and CS APIs are slim to none. CS has many of the
Features that we need. While using Unreal would produce ultra-realistic scenes, there are 2 things that should be remembered: 1. that it can only do this on the best macines; 2. that it can only make it as good as the models.
Like I said earlier, if anyone can convince them to let the FIRST community is it for this dirt cheap, I will be more than happy to use it. but until then, I know I will not support it.