If each row goes 1 circle, 2 circles, 3 circles, the missing picture at the end of a row has 3 circles.
Check the other things too, such as colour and size, one at a time.
A 3×3 grid of pictures follows a pattern, and the last picture is missing. Pick the picture that fits.

Work out the rules in a 3×3 grid of figures and pick the figure that completes it.
If each row goes 1 circle, 2 circles, 3 circles, the missing picture at the end of a row has 3 circles.
Check the other things too, such as colour and size, one at a time.
Classic
A fixed number of rounds, then a results screen.
Endless
Keep playing until you press Quit.
Time Attack
Fit in as many rounds as you can before the clock runs out.
Survival
Play until you run out of lives or make the game-ending mistake.
Still stuck? The team usually replies within one business day.