Spot it: the two pictures are almost the same. Tap each difference, in either picture. Found ones get circled in both.
The spliff is your timer. It burns down while you look. Find every difference before it's cashed to clear the level. Pick how long it burns on the start screen: Casual 10:00, Standard 7:10, Harder 4:20 or Lightning 1:00 per level. Each one keeps its own best score.
Wrong taps burn 5 seconds off the spliff, so look before you tap.
💧 Eye Drops clear the haze around one difference for a few seconds (or press H). You start with 3 and get one more for every level you clear. A difference found with drops scores less.
Bonuses: find differences quickly one after another for Quick Eyes points. Leftover time scores at the end of a level (up to a minute's worth), and a level with no wrong taps and no drops is Perfect.
8 scenes, then Round 2: the same places with new differences, and more of them.
Level Builder: make your own level from the start screen. Pick a backdrop, drop stickers on it, then in Differences tap a sticker and change it in the top or bottom picture (hide, recolor, flip, turn, resize or swap it). Make 3 to 9 differences, Test it, then Share the link: whoever opens it plays your level.