I don't think it needs more mechanics, what you have here is good and I don't see any real need to add additional elements to gameplay.
I'd say for me personally the overall length of each attempt just feels too short. I want to keep playing but as soon as I find myself getting into the groove of the gameplay it just kind of comes to an abrupt end. I wouldn't say it needs a lot but I would like too see the what is here extended into a longer experience.