Beginner Combat Robot

My young son is undergoing surgery soon and will be on bedrest for a few weeks. He is really into building lego robots with his dad and the Vex robot kits. 
But he wants to start doing real robots and learning the electronics and programming (which his father is well versed in).

I saw the beginner bot kits suggested here but none of them do any sort of shooting or hitting type things that he is looking for. He really wants to start getting into combat robotics. Is there a good kit that I can buy to get him started or an addon kit I can buy? 

Or if there is a book or instructions that let me buy the parts separately that is fine too. Just really looking for something that will challenge him, keep him occupied and give him something to do while he's unable to do much else.

Thanks for any help or suggestions!

SERVO

I would strongly suggest he check out “SERVO” magazine put out by the same folks who produce Nuts & Volts. Each issue has articles on building combat robots and advertisers who sell parts as well as complete kits. Please be forewarned, building large robots is neither easy nor cheap so he needs to have enough enthusiasm, determination, and money to see the project through or he is sure to be disappointed by the outcome.