Scriptable TD

This is just the beginning of an idea, but hopefully I or someone else can implement it. I thought of it while playing fieldrunners. I don't like how the towers decide who to fire on. My solution? Scripts that can be applied to towers. Somewhere in the app you would be anble to write simple code, preferably visually so anyone can do it. These scripts would allow if/then, loops, goto, and variables. This would give the user unlimited control over their towers. They would be able to save their scripts, and each tower would have an accessible option to set a script to use.
I'm sharing this because though I have plans to start my own TD with an original feature, not including this, I just don't think I could implement what I just said. Hopefully one of you can.
Nate