If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
You're the last surviving sorcerer's apprentice of Sorth, the Dark Lord of Castle CantSayTheNameOrIHaveToDie. Whilst cleaning the library, you dropped the "Dark Grimoires of Sorth" to the ground and all banished creatures could escape. Now it's on you to clean up the mess.
Make your way through the castle and look for all escaped creatures and push them to their pentagrams to ban them back into the Dark Grimoires of Sorth.
Arrow keys to move cursor.
Space bar to select and release dragon