A many-segmented crawler snakes down through a mushroom field — shoot a segment to split it in two and clear every piece to survive the wave.
Touch and hold anywhere on the lower screen to slide your shooter left/right toward your finger — while you hold, it auto-fires bullets straight up. Shooting a crawler segment kills it, drops a mushroom in that cell, and splits the crawler into two pieces; the back piece reverses direction. Crawlers hitting an edge or a mushroom descend one row. Shoot mushrooms (four hits) to clear paths. Wave ends when every crawler is gone — next wave brings a longer, faster crawler. A crawler touching your shooter costs a life; three lives total.
Splitting near the middle is better than the tail. Killing the tail just removes one segment; killing a middle segment creates a smaller crawler that's also forced to descend (mushroom rule). Two small pieces hit the bottom faster than one long one, but they ALSO finish much sooner — pace yourself.
Don't shoot every mushroom you see. Each mushroom is also a built-in deflector that helps trap the crawler into descending. Clear only the mushrooms blocking your firing lane straight up to the head; leave the ones to the side as built-in walls.
Mid-screen is the most dangerous position. The crawler can drop onto you from above OR loop back from the side. Stay low and use mushrooms in the middle rows as visual rails — the crawler bounces off them predictably.
Watch for descending crawlers, not the ones above you. A crawler at row 3 can't hurt you yet — the one at row 12 is the immediate threat. Always shoot the closest crawler first, no matter how big the one higher up is.