First of all.. Thank you so much for playing the game till the end!! I was so worried that because I didn't get any time to balance the game properly no one would play it till the end. And yes you did actually complete the game, the goal was to reach the right end of the screen. I don't know why you weren't prompted to the win screen. I will definitely look into it.
About the airships. They do work. They are supposed to be placed by the player do take a hit from the enemy giant cannon (as to protect your build) so I set their damage to be very low, Because their main purpose was to defend.
I had different plans for the circle block. It was suppose to summon a free airship every time the clock hand completes a round (the circle block is actually a clock). But unfortunately I didn't have enough time to implement that as I only had 3 days to work on this game :(.... So in a rush and to give them a purpose I did what I did lol.
I know the game is not balanced at all and a lot of people have mentioned that. The unbeatable horde of ships in the end is one of them. Really sorry!! XD. I do plan on working on it further. maybe after the jam I'll release a proper balanced, well thought out version of it(with music).
Thank you for your review.