Once you start buying new ball colors, experiment with different ones to figure out which ones make it easier to see. Some of them are a solid grayscale, while others are a swirly grayscale. Some of them are a solid color, while others have a color with marble-like swirls. Still others have more than one color in a varying pattern, from grayscale to color to grayscale AND colors.
Generally, the ones that will help the most are the swirly or patterned ones, because you will be able to see the pattern moving while you roll the ball around. The higher the pattern contrast, the better. It helps stop from getting tunnel vision. Color patterns are often considered the best as well, because it is easier to see a bright color, such as yellow, over the bursts of the crystals when you hit them.
Watch out for the color changes, because they get tougher and tougher to see against as your score gets higher and higher. In particular, once you hit 400, the path turns white, so the only way that you can see the path is by the shadows that it casts. It will change again once you get to around 450, but watch out because up until then, that’s one of the toughest paths to traverse.
Want a sure fire way to slow the game down? Simply download some insanely graphically intense game, such as Rival Knights or some other PS3-esque game, then play it for a bit, then have it on in the background while you play ZigZag. This is almost guaranteed to slow down the app and make it real easy to score a ton of points.
To make it a little bit easier to see the board on small phones, such as the iPhone 5S/5/5c and older, go to the settings, then accessibility, then enable zoom and the screen will appear just a little bit bigger. Center the zoom on the top center of the screen so that you can see as much space in front of you as possible.
If all else fails, go ahead and use a hex editor app to mess with your high score and try to get it into Game Center. Your best bet is to load the game up to your computer from your phone or tablet, then edit the code when you find it, then delete the game from your device. Then load it back onto your device from the computer (not from the app store) and your high score will be on there.