Infrared (BTD5)

 is an achievement in Bloons TD 5 Mobile and both Bloons Monkey City versions. It is unlocked by popping 250,000 Camo Bloons (1,000,000 in Bloons Monkey City). Doing the mission Covert Pops a few times will make this achievement really easy to obtain as all the bloons in that mission are Camo Bloons.