Some years ago I built a digital piggy bank to help people save money automatically. The psychology behind the product is really hard. The biggest challenges is that you only see the value of saving money after a long time. Everybody knows they should do it, but it's easier to postpone as it's painful and hard to do in a daily basis.

Yotta solves this with an amazing approach. You get the long term reward of saving money at the some time that you get the exciting possibility of winning a short time reward. It's genius.