This green common hostile mob is called Creeper and he is from the cool computer indie game Minecraft. When approaching the player, the Creeper will hiss and explode after 1,5 seconds. Interestingly, when detonated, the sound is similar to an ordinary explosion but shorter and softer. And a pixel green Gun is perfect for Creeper. The game Minecraft cursor and pixel pointer with Minecraft Gun and Creeper!
