An acting wall is a tile other than the nine types of walls, which nevertheless acts as a wall to an object. (This does not include tiles which would destroy the object; even though it is undesirable, the object can still move there.)
Some acting walls are effective against only one object, and sometimes all three but with specific provisions as to when it acts. There are three types of acting walls: those against Chip, those against blocks and those against monsters.
- Socket, only if Chip still needs more chips.
- Lock, only if Chip does not have a key of its color.
- Other natural Chip tiles.
- Other monsters
- Recessed wall
- Computer chip
- Random force floor
- Fire, only to walkers and bugs.
In Lynx, there are some additional rules; the random force floor allows monsters through, and the following are also acting walls:
Additional Lynx monster-acting walls
Additional Lynx block-acting walls
There are some tile combinations which are acting walls, and some walls which are acting walls only to some objects. A block on a trap is an acting wall to everything as long as the trap is unreleased. The blue wall is a related concept known as acting dirt: it is an acting wall to blocks and monsters, but allowing Chip through and then disappearing just like an actual dirt space.