Very cute art, simple but challenging gameplay. Overall well done, I had fun playing your game! As several comments already mentioned - there's too little time to react to new information (where the hand is spawning, what the new keys are). Also, perhaps an easy way to make the game easier and also more interesting at the same time is to add health and health pickups. Then the player will have some leeway if the key switch messes them up, and it also gives them incentive to switch lanes other than just dodging obstacles. 

Very original entry, I like the idea although I'm not really good at the game. The music and the art style are superb! Great job overall keep it up :)