The ghost is a type of monster introduced in Chip's Challenge 2. A ghost's movement functions similarly to a glider's in that it will turn left at any acting wall tile, right if the left pathway is blocked, or backwards if both the left and right directions are blocked. However, ghosts will pass through most acting wall tiles, ignoring them completely. Their movement behavior is among the most complex in CC2, along with rovers.
Ghost movement behavior
Ghosts will pass through most tiles, ignoring them completely. These tiles include most wall tiles, obstacle tiles (aside from water), most floor-acting tiles (such as gender-only signs), time modifiers, dirt, gravel, hints, thieves, bonus flags, swivel doors, locks, railroad tracks, the transmogrifier, chips, sockets, and exits.
Ghosts are able to activate switches and buttons, including the yellow button. Ghosts can enter empty clone machines, which renders them stuck and converts the cloners to ghost cloners. Ghosts can pick up and utilize every item, including every key except red. If a ghost picks up an item, it can utilize said item the same way Chip can. For instance, if a ghost picks up a blue key and then is directed into a blue lock, it will open the door and use the key. Ghosts can also use teleports in the same manner and will pick up yellow teleports when possible. Should a ghost's inventory contain four items, it will drop the first item upon picking up a fifth. If the dropped item is a time bomb, the item will remain inactive and is able to be picked up by Chip or Melinda. However, dropped bowling balls do become active (and the ghost will probably "trip" over it and die).
Acting walls to ghosts include the following:
- Custom walls and custom floor
- Water and turtles
- Steel walls
- Blocks, ice blocks, and directional blocks
- Other monsters, including other ghosts
Ghosts change their behavior when they pick up most kinds of boots. If a ghost has fire boots and passes over fire, the fire will turn to floor. With flippers, a ghost can pass over water but will still avoid turtles. With hiking boots, a ghost will remove dirt when passing over. A ghost without ice skates will maintain walking speed (5 m/s) and reverse direction if it's on ice and collides with an acting wall (ghosts pass through ice corners). If the ghost has ice skates in the same situation, it will be trapped in place, similar to most creatures' interactions with railroad tracks. Ghosts cannot lose their items to thieves.
Ghosts interact with many tiles differently if there are no signs on them, regardless if they have the forbidden item. Generally, tiles that are acting walls to other monsters become acting walls to ghosts.