Maybe i'm just dumb, but i just went round in a circle getting the coal and putting it in the furnace, until no coal was left.. I don't really understand
At the start we wanted to make more obstacles like the aliens, but didn't have enough time to put them in the game.
The point of the game at this moment is to get the highest score you can, while destroying the alien ships, but we might have made it a little bit too easy.
