I played a lot of Command & Conquer when I was younger, and I remember going through the files for C&C: Red Alert. I found one that had all the units names and properties, and wondered what happened if I changed a value. So I changed grenadiers attack speed to something ridiculously fast, and found that it actually changed it in the game!

The light bulb went off in my head, and I then created new units:
- Albert Einstein that shot electricity
- Attack dogs that launched missiles

Granted the animations didn't exist for these so it defaulted to playing their death animations when attacking, which was amusing.

That was the ah-ha moment for me that lead me to pursue programming. It was just so much fun!