>>15758242Unlimited puzzle is actually the easiest for me if I dont want to pay 100% attention so I can react fast enough. It takes the longest though. The trick is simply to not flip mindlessly. If you didnt mix them up and immediately start putting the right pieces you fix 2 per flip and get bonus seconds.
It's all about memorizing the border patterns and it's better to spend some time thinking than randomly flipping like an idiot.