The connection between fins and directions wasn't communicated that well. Showing it like you did after the first fin left the impression that I can now move in three directions opposite D,S,A being left, forward, right respectively (which led me to assume randomized controls possibly because I've seen that in many games this jam). Also since it's quite dark I honestly didn't even notice the fin.
But once I tried the game again while understanding the rules it was fun. Became way too easy in a minute or so though. Maybe in the future the enemies should also evolve.