I have about $150 to spare on increasing my library of books and wanted some recommendations of general game programming books to look at. What I mean by general, is something that is going to be helpful not matter what engine I plan on using. Right now I am using the Unity engine and plan on using it for quite some time so right now I would not really want a book of low level OpenGL/XNA/DirectX or any real API specific books as their usefulness would be limited for me at the current time. I am looking for books on stuff like AI, indie game development, etc... or anything else that can be applied generically. One of the books I will be buying is: http://www.amazon.com/exec/obidos/tg/detail/-/1556220782/ref=ord_cart_shr?_encoding=UTF8&m=ATVPDKIKX0DER&v=glance Any other recommendation would be great. Thanks.

I would say Game Physics by Dave Eberly, but It's a bit maths intensive, if that's your sort of things.

Also, you can look at the Book recommendations here in gamedev to narrow your field of interest, because there are dozens of books worth reading, and they aren't $10 each!

just to chip in and say that Game AI by example book is a beautiful read, got it a few months back

after that i'd probably say something on design patterns since they're always useful to know

the finite state machine pattern on it's own has reduced code spaghettification by a factor of (orgasm times anger)+awesome