Revisit

Maybe helicopters? But I don't know where thrust would fit.

Actually I sort of made it kind of a zero-g 3D based system. The old version was going to be an actual flight based system, I even had front-back, rotation and so forth.

But I decided for a game that is suppose to be fun to play, that it wouldn't be with that. I removed all concept of front, back, top, bottom, left and right to simplify things.

Something I realized in hindsight with BerryBots is that a simpler API doesn't necessarily mean that it's simpler for the client of the API. In many cases, even the opposite. Consider that the "API" (instruction set) of a CPU is a hell of a lot simpler than the Java API, but for any real application I'd much rather be working with the latter. I kept the movement API in BerryBots to a single method to fire a thruster that alters your trajectory, but as a consequence you have to kind of understand vectors to make full use of it.

I'm not saying that you should make a user deal with complex 3-D physics or anything, just that there's a sweet spot.