If you are confused: ▲ → ■ → ● → ▲
And don't forget : ▲ ← ■ ← ● ← ▲
This was pretty fun. The controls felt intuitive once you inverted them. One thing I would recommend is instead of using the fuel over the course of the whole game use it as a booster or extra flight time. Integrating it into the level design (like a coin pickup in super mario) would make it more approachable/casual.