I understand not having instructions in the game.. sometimes the deadline comes too fast. But why not put some description or instructions on the itch.io page itself? On my second attempt, I figured out that I stand in the middle and click the mouse on ghosts who arrive. I should click on them as soon as I see them before they get a chance to break through my defences. If they get to me, it's game over. Highest score: 44. I don't know if there's a win-condition.
The art is nice. I liked the little whirlwind sprite for keeping the ghosts away. With a bit of audio and some instructions, and maybe a goal, it could be a pretty good game.