I am all about people using, hacking and expanding on this or any of my games! I love that stuff! :-)
I don't care very much about how you mention me: "inspired by/based on T-DEF by Lari Assmuth" or pretty much whatever is fine! And it's not a requirement either but on principle I like it when people credit their sources of inspiration.
And if you do make something please tell me about it here or on twitter so I can come check out your project and boost it with what little reach I have! :-)