Woo, two interested ones! High five, now. o/
Anyway, let me tell you about some of the problems i'm having.
I haven't implemented friction because i thought setting the ball to bounce against the wall would work out alright. Later, i added the create event with the gravity set to 5, so the ball would go down instead of bouncing everywere. I didn't figured out WHY it just kept going up afterwards. If it goes too fast, it'll enter the speed of light and actually exit the stage entirely.
The dots are just little time killers to test out the movement. The left and right movements have left and right sprites each, thanks to the change sprite function. Other than that, they have the go left and go right functions with the press of the corresponding keys, and a 'no movement' function when you release them. Another problem is that if the ball is bouncing really high, and i release the movement key when it's close to the ground, it'll just stall there and reset the bouncing to that height. It's weird.
Also, this is irrelevant, but the dots have a create event with the set score function to relative 10. However, when they're 'created' again after catched, they don't update your score any further. It just stays at 20.
But yeah, the game will use the engine you suggested. Who should i credit for the work?