I know a lot of people are going to say Python, which I would normally agree with. In this case though, I would almost say that some kind of Lisp might be a go

I know a lot of people are going to say Python, which I would normally agree with. In this case though, I would almost say that some kind of Lisp might be a good idea. The lack of a complex syntax means you can just get started hacking around, and it would definitely "keep your brain moving," as you say. Some kind of Scheme would probably be best. Racket, especially, is supported cross-platform, has a nice little IDE, and has plenty of libraries and community support.