I was playing around with a sort of hovercraft (was more like a platform) using rockets and making a sort of landing pad, then one idea led to another and I created a sort of simulation of a sea voyage.
Since I haven't fully mastered the various types of force engines possible in the game (probably only a few), I used one that I knew to make a sort of reciprocating engine (not sure if that's the correct term) to produce the back and forth movements.
I know it's somewhat crude, but still pretty innovative I would say