You should already have a maze game working.

Lets see how to make it more challenging by including a monster.

Add a sprite that will be your monster.
  1. Click Resources.
  2. Click Create Sprite. 
  3. Load Sprite.
  4. Click the monster that you want to use.
  5. Click Open.
  6. Change the name to Sprite Monster.
  7. Click Ok.
Add the Sprite monster as an object.
  1. Click Resources.
  2. Click Create Object. 
  3. Change the name to Object Monster. 
  4. Change the sprite to sprite monster. 
  5. Add a "create" event.
  6. Add a movement action. 
  7. When you add the action select all the arrows at a speed of 2. 
  8. Add a collision event with walls. 
  9. Drag a bounce action over. 
Add another collision event with the person.  This is where we tell the monster to kill the person.
  1. Create another collision event with Object Person. 
  2. Go to the Main 1 Tab of actions. 
  3. Drag destroy the instance over to actions. 
  4. Click Object.
  5. Click the drop down arrow and select Object Person. 
  6. Drag over Restart the room. 
Place the monster in the room and your done.

My room looks like this.