Each round is a new maze. Take a look first: the clock only starts when you press.
Click and hold the green S in the top-left corner (on a phone, touch and hold). You have 45 seconds from that moment.
Keep holding and draw a line through the maze to the yellow E in the bottom-right corner.
If the line touches a wall, or you let go before the E, the round fails.
Tips
There is only one way through, and every wrong turn is a short dead end. Trace the route with your eyes before you press.
Stay in the middle of the corridors and ease off at the turns: corners are where lines clip walls.
Only the desktop maze (33 by 19) is ranked, so everyone on the leaderboard drew the same size of maze. Phones get a smaller maze that plays the same but isn't saved.
The leaderboard ranks clears first. Among clears, the faster clear ranks higher.