I would like to give you some ideas. For instance: sometimes water fills the drum and player has to run to the top, or water drips coming from the drum so make game a little more harder. And add soap to the surface where player runs to make it slippy. Maybe you will add extra levels like dishwashing machine or smth. I hope i gave you some ideas, and i ask you to check my project too to get some criticism from your team. Good luck!