Don't recycle water, it slows down the animation, instead make the wave maker a killer and use a water sporner to create the water. Then less water is used at a time. Also, if you add a adjustable nosle to the water sporner you can direct the water further up or down for the surfer.
I stole it from my circle course. Behind the circle is an imortal rectangle, when the circle hits the killer flames the circle is destroyed leaving the rectangle saying 'you lose'.
The rectangle also weights down the circle so it can't fly.
I'm supprised you didn't ask about the explosive, its a far more complex mechanism.
I you had a counter that meansured the number of balls you could make a graph whereby the number of circles affected the size of a spring attached to a block with a tracer, if this contraption moved along on wheels then you could measure the rise and fall of your 'lifeforms'. Without sounding boring you could make studies into the rise and fall of populations relitive the food source. If the food sources regenerated and the cirlces did not 'breed' straight away then soon your simulation would become quite accurate.
With most engines represented by many different authors this complex engine is unique as only you have managed (or tried) to represent the heated gas that powers it.
It does exactly what it says it does, it brakes. I hoped you meant 'slow down' by brakes by clearly you meant 'flip upside down whenever you press any button'.