This engine certainly has a bright future.
So far in development stage, but engine is great so far.
How it works:
Laser hits blue polygon and changes collision set of black cylinder box. This pushes the cylinder down, giving it energy. When laser hits red polygon, collision set of black cylinder box is set back to 0, leaving room for the cylinder to rotate back up to original position. Repeats this process.
I love this engine I made because it uses next to nothing resources (16 objects), uses seriously basic scripting and can give great power (once I finish developing it).
100% reliable at sim.frequency = 100, I haven't tried any other yet.
I think with more cylinders it will be great!
Operation:
S - starter button
Down - engine break (toggle)
To start, release engine break and press S. Let engine run for as long as you like!