As you watch the radar screen, you can see which enemies to attack first. With every 10 000 points, you get a new ship and a smart bomb. Each wave only ended when all enemies were eliminated, at which time the wave number appeared on the screen. Sometimes, the screen is so overrun by aliens that using a bomb to kill them was the only option. Hyperspace could be your best option to escape the situation, even if it doesn't take you anywhere safe.