Reservoir

Reservoir is the thirteenth level of Bloons. In order to win, you must pop the bloons by shooting through the gaps in the metal box. Popping the Tack Bloons, which are only accessible by the smallest hole will result in popping 25 bloons, which is the minimum popping requirement, making you win instantly. It is still possible to win by just popping the regular bloons by shooting through the three and two block wide holes.