Border Patrol

Border Patrol is a special mission in which you must prevent twenty rounds of bloons from crossing a border. The track for this mission is entirely land, and has a border line across the middle from left to right. The bloons spawn at the top of the screen (the position from left to right is random). You can place towers on either side of the border, but if bloons cross it, you lose half the lives they would normally cause you to lose. Then, if they reach the bottom of the screen, you will lose the number of lives you would normally lose (so, in total, you lose 1.5 times the normal number of lives). You start out with 140 lives. If you complete the mission, you get $240 Monkey Money.