Rattlebones was good fun, and fortunately, other than the interchangeable dice, had nothing in common with my game. So I put pen to paper. (Or keystrokes to a keyboard.) 

The birth of the idea for IMDL!, which actually hasn't changed through the many versions, was:

• Enemies invade earth

• Players take the role of a Mech warrior

• Players upgrade their mech and corresponding dice

• Players kick enemy butt.

• Rinse and repeat against harder enemies with bigger and better mechs.

I knew I wanted an international feel, and I knew wanted to see the mechs grow. How that was going to work took the next couple of months to figure out...