Really enjoyable game! It's visually polished and is just fun.
I the arrow keys are should have been different keys in my opinion (it looks great when the arrows come down but pressing the real physical arrow keys on my keyboard is rather uncomfortable, instead d, f and j keys would have been great a choice)
Levels/Stages would have been great.
The first 3 People are easy to do flawlessly. But afterwards the difficulty ramps up mercilessly. With the option to jump to a later point in the game you have less repetition which leads to more time enjoying the game.
Pressing all keys at once seems to work, you should fix this bug.
Real good game guys!