Source: Wikipedia, Chaos Strikes Back , available under the CC-BY-SA License.
Chaos Strikes Back is an expansion to Dungeon Master, the first 3D real-time action computer role-playing game. Chaos Strikes Back was released in 1989 and is also available on several platforms (including Atari ST, Amiga, X68000, PC-98, FM Towns and PC). It uses the same engine as Dungeon Master, with new graphics and creatures.
Whereas the first game saw the player following a fairly linear path through the adventure, with the completion of each flat level marked by a staircase leading down onto a new slightly harder level below, Chaos Strikes Back features a choice of paths which twist back and forth over all levels. The puzzles are far more convoluted, often demanding quick mastery of the control system to deal with intense combat, along with brain vexing riddles and room layouts.
The game is therefore pitched at a much higher difficulty level than its predecessor. The player can choose from a selection of moderately high-level characters or can import characters from a Dungeon Master saved game. In an indication of the game's uncompromising toughness, the player's very first task is to get out of a dark, enclosed room filled with ferociously toothed man-eating giant worms. The game is made a little easier by the inclusion of a separate program which dispenses cryptic hints based on the player's current saved game.
The player's task is to collect four pieces of corbum, a magical material from which the eponymous Lord Chaos draws his power. This requires the traversing of four separate paths each leading to a piece of corbamite and each themed around one of the disciplines open to characters in the game. These disciplines are fighter, wizard, priest and ninja (as with many role-playing computer games of this period, a great though unacknowledged debt was owed to Dungeons and Dragons, of which Chaos Strikes Back has plenty of both).