Nice little game. I like the roll-back effect when you die.
Although, don't add new characters if they're not going to do anything. Currently they'd be just different ways to obstruct view and I'd pick a small rolling ball over Darth Vader anytime, just so I could see better. But you could add special ability to each character to make them worthwhile. For example, with Darth Vader, a large 'force' leap every 20 seconds. Or a lightsaber slash removing obstacles in the near vicinity usable every now and then.
Your Project System's game window resolution seems oversized though. It's roughly 1300×700, but the actual Unity game is 960×638.
In general, I think the jump is too dangerous to use (not very long, and unreliable – try jumping quickly, several times in a row) and left/right movement sometimes wasn't as fast as I hoped it would be. I'm also not sure what the blue boxes do. You can crash into them, but they neither help nor harm you.