Tiny Zombies were about to enter your house. You used Peashooters, Lily Pads and Wall-nuts to fend off the little zombies. The game would have given you many Cherry Bombs if you saved them from the zombies. You used four Peashooters in a lane to shoot the Football Zombies. You couldn't get another Cherry Bomb if you used all of them.
The reason why PopCap replaced this mini-game, because it would have been too difficult for you to see the mini-zombies on the DS screen.