I suggest you have the color of the text not correspond to the color players must choose. So, if the safe color is red, you might display : RED
This would provide a real, satisfying challenge and would allow you to remove the frustratingly annoying events like random rockets, guns, snowballs, and pushbrooms.
Another suggestion: either make the corners smaller, make them further away from the center of the arena, or specify a single corner. At the moment the middle/corner events don't do much.
If you want to really make things interesting have the colors of each pad change randomly after each event.
