Green Monster 4 - All BOSS is an Android game developed by IDLERO, which falls under the action subcategory of games. In this game, players must survive the abandoned lower levels of a haunted kindergarten. The monsters that were once gentle and docile have mysteriously grown hostile, and most of them prey on the protagonist when he enters the kindergarten to find his missing child.

In the previous chapter, players explored the abandoned levels of the kindergarten, survived the residents of the establishment, and uncovered the truth behind the place. In the 4th chapter, players are required to delve even deeper into the levels of the mysterious establishment that is the kindergarten. The game features an entire underworld for players to explore and survive, with countless traps and over 111 challenging levels waiting for them to discover.