Stage 3 Clear Tip (Very Very Small)

Premise: I don't like watching ads, so I didn't watch any for extra rewards. This is how I cleared Stage 3. I kept hovering around the 'blue circle', utilizing the characteristic that monsters only move straight. Some monsters were blocked by the net 'white circle' and couldn't get close, but they were still within shooting range. Occasionally moving below the blue circle could lure monsters blocked by houses closer to you, but they were still blocked by the net. Once the monsters were dead, I could collect blue gems by getting close to the net.