If your character has a different sprite or sound for the mechanics then be sure to make a different sprite inside the project and also add a sound in the project as well if you have it so I can add it into a game. You can also have a mechanics that your characters can appear when the player enters a room or something like that as well and remember that this is not a scratch game. It's a Unity game. This characters will be added in the V1 of the game.
Easy: 10 Seconds Medium: 15 Seconds Hard: 20 Seconds Very Hard: 25 Seconds