1. Create a circle sprite the size of your explosion radius and set its opacity to 50 for ease of use.
2. Set it to invisible by default (left side properties).
3. Spawn it at an image point center of the sprite "bomb" that goes off.
4. Do Is-overlapping check and destroy anything is touches that needs to be kilt.
5. Destroy radius sprite.
Your game making has just been hacked!