wallhack A form of game cheat especially associated with first-person
shooters like Quake, in which the walls in the simulated maze or dungeon
are rendered transparent to the cheater. This gives the cheater normally
hidden information about the whereabouts of other players. Beyond gaming,
a wallhack is the paradigm case of a whole class of security problems that
stem from the fact that a server cannot trust client software, and server
authors must assume that all computation farmed out to a client is exposed
to and can be interfered with by the user.