Tile World is a tile-based computer puzzle game designed to emulate the commercial game Chip's Challenge. Tile World was written by Brian Raiter in platform-neutral C and SDL, and licensed under the GPL. (To avoid copyright infringement, Tile World does not use the original graphics, sounds or music from the game being emulated.) It is currently supported by Brian on Windows and GNU/Linux. A Mac OS X port is maintained by a third party and a 2002 version for BeOS remains available.
One of Tile World's useful features is the ability to load user-created levelsets easily, without the renaming of files that is necessary in Microsoft's version of Chip's Challenge. Tile World also stores a replay of the player's fastest solution to each level, as well as showing time statistics for untimed levels (it treats them as though they had a time limit of 999 seconds). Starting around April 17, 2006, version 1.3.0 of Tile World also has a database of known unsolvable user-created levels, so that whenever a level in the database is encountered by the player, Tile World will let the player skip the level (by providing the password to the next level). 
Tile World has two rulesets intended to emulate two different implementations of Chip's Challenge: the MS ruleset emulates the Microsoft Windows implementation of the game, while the Lynx ruleset emulates the original game for the Atari Lynx. This is because the two versions have many differences.
Under the MS ruleset, the player and monsters move one tile at a time, in effect disappearing from their current locations while simultaneously appearing on their destination locations, without any between-tile animation frames to smooth out the movement. Many bugs from the Microsoft implementation are also emulated, in order for scores obtained from Tile World to be consistent with that implementation.
With the Lynx ruleset, all objects move smoothly from one tile to the next. The Lynx and MS rulesets also has a variety of subtle differences in how monsters and other game elements work. For instance, in the original Lynx version, most monsters avoid fire; in the MS version, most monsters enter the fire and die. In addition, in the Lynx ruleset only a restricted subset of tile objects, which include Chip, monsters and blocks, are allowed to coexist with other tiles at the same location (eg. Chip on ice). The Microsoft implementation however uses two layers of tiles, therefore allowing all possible combinations of 2 tiles to coexist in one location, as can be seen in many fan-made levels. The Lynx ruleset does allow some things the actual Lynx implementation of the game does not, such as arbitrary connections of buttons to traps and clone machines (in the actual Lynx game the connections are made implicitly based on positions of the buttons and objects), a concept borrowed from the Microsoft implementation.
Occasionally a discrepancy is discovered between one of the rulesets and the game it attempts to emulate. The MS ruleset, being more popular, tends to receive far more scrutiny.