Demons Castle is a free simulation game developed by Glasshead Co.Ltd. for Android devices. In this game, players must add new floors to the castle and summon monsters to defend it. The goal is to gain "Demonic Power" by defeating humans and using it to level up the monsters and extend the castle.

To gain Demonic Power, players must tap on the Demons Castle to add a new floor and summon a monster. Once the monster is summoned, the player can tap on the "brave" button to send the monster to defeat the human braves. This will let the power of the Demon lord know all over the world.

Overall, Demons Castle is an enjoyable game for those who like simulation games. The graphics are decent, and the gameplay is simple yet engaging. However, the game can become repetitive after a while. If you are looking for a fun game to pass the time, Demons Castle is definitely worth a try.