I really enjoy this app for what it is – a simple, minimalistic puzzle app that makes you think. You can rush through by trying to beat levels or be a perfectionist and try to meet all three criteria in each level for a real challenge. The levels are quick and made for quick gameplay when time allows. One issue though is lacking explanation for some game features, though it can be figured out quickly. Excellent minimalist approach with simple, strong mechanics. OCO gets a 7/10 with room to be an easy 8 with some minor improvements in future updates.