Nice! I really liked this mechanic. The upgrades definitely felt like they made an impact on the game, even with something as small as an increased radius. I also think the 5 coin play cost can help encourage people to actually try to blow up more gladiators rather than repeatedly only getting one or two, and it was fun to herd a bunch of them in a corner and explode them all at once! The highest I got was 10. Good job on this!