itch.io

I like the challenge. Maybe the sub could have physics where, once moving in one direction, it wants to continue moving in that direction. This would make it take some time to accelerate in the other direction. Also, it would be cool if the current underwater had gaps so you could avoid them, that way the sub-drift would make it a challenge to avoid the currents.  

I agree with @Jaxah about the movement of the craft being too twitchy. The game has promise and the visuals are good. The choice to defend or invade is compelling. I was not ready for the music, but I appreciated the whimsicalness of it. The high score vs the health needs to be separated, in my opinion, and more differentiated for clarity. You have a possible addicting game here and I would like to see the progress you make on it.