Adventure

Adventure is a 1979 video game for the Atari 2600 video game console. In the game, the player controls a square avatar whose quest is to hunt an open world environment for a hidden magical chalice, returning it to the yellow castle. The game world is also populated by roaming enemies: dragons, which can eat the avatar; and a bat, which randomly steals and hides items around the game world. Adventure was conceived as a graphical version of the 1977 text adventure Colossal Cave Adventure. It took developer Warren Robinett approximately one year to design and code the game, during which time he had to overcome a variety of technical limitations in the Atari 2600 console hardware. In this game, he introduced the first widely known video game Easter egg, a secret room serving to credit him for the game's creation. As the first action-adventure game released, Adventure sold more than a million copies and essentially created the genre. It spawned a handful of official and unofficial sequels, and has been included in numerous Atari 2600 collections.

According to the game's instructions, an evil magician has stolen the Enchanted Chalice and hidden it somewhere in the kingdom. The player's goal is to find the Chalice and return it to the Golden Castle. The player character, represented by a square avatar, explores a multi-screen landscape containing castles, mazes, and various rooms, with thirty rooms in all. Hidden throughout the world are a sword, keys that unlock each of the three castles (golden, black, and white), a magic bridge that allows the avatar to travel through barriers, and a magnet that attracts the other items toward it. While Robinett originally intended for all rooms to be bidirectionally connected, a few such connections (including one inside the White Castle) were unidirectional, which he considered to be bugs. Such problems were explained away as 'bad magic' in the game's manual.

Roaming the world are three dragons:

Yorgle, the yellow dragon, is afraid of the gold key and will run from it. He roams the game freely, but can guard the Chalice or help the other dragons guard items.
Grundle, the green dragon, guards the magnet, the bridge, the black key, and the chalice.
Rhindle, the red dragon, is the fastest and most aggressive. He guards the white key and chalice.

The dragons have four possible states, all indicated with different sprites: chasing the player, biting, having swallowed the player's avatar, and death. When initially encountered, a dragon is in the chase state. When a dragon collides with the avatar, it will enter the bite state, freezing in place. After a fraction of the second, the dragon completes the bite. If the dragon has a second collision with the avatar at that moment, it swallows the avatar, who becomes trapped in the dragon's belly. The delay between biting and swallowing is shorter if the console's left difficulty switch is in the 'A' position. While biting, a dragon cannot be killed.

When eaten by a dragon, a player need not start a new game. Hitting the game reset switch reincarnates the player back at the Yellow Castle. As a penalty, any dead dragons are reincarnated as well; the objects all remain in place at the time of the player's death, including whatever items the avatar may have been carrying. This is one of the earliest usages of the 'continue game' feature, now common in video games. Hitting the game select switch after death returns the game to the game select screen, losing the current game's state.

The sword is used to kill dragons. Later video games use the concept of bounding boxes—if invisible rectangles surrounding objects overlap, it counts as a hit—to determine if an attack succeeds; the sword in Adventure only registers a kill if one of its individual pixels overlaps with one of the pixels of the dragon being attacked. While this method is more accurate, it is more processing intensive and makes successful attacks more difficult. The arrow-shaped end of the sword was designed to improve the chances of scoring such a hit. If the console's rightmost difficulty switch is in the 'A' position, the dragons will run away when they see the sword.

A black bat roams the entire game world randomly carrying any single object, including live or dead dragons, which it occasionally swaps with another object along its flight path. The bat was the first video game character to have two possible states: agitated and non-agitated. In the agitated state, the bat is ready to swap items. In the non-agitated, or ignore state, the bat is content with its current item. This ignore state lasts for about ten seconds, to prevent the bat from getting stuck in a single room swapping back between two items endlessly.[8] The bat can swap items even in areas where the player is not present. The bat was added to the game with the intention of adding unpredictability and confusion to the game.

The bat continues to fly even after the player has been killed, and occasionally the bat will pick up the dragon whose stomach contains the player's avatar, giving the player a whirlwind tour of the Adventure universe. The player can sometimes trap the bat inside castles, or can capture and carry it. The creature's name was intended to be Knubberrub, but that name was not included in the manual.

There are three different games available via the game select switch:

Level 1 is a simplified version of the game and does not have the red dragon, the bat, the catacombs, the white castle, or the maze inside the black castle. The objects in game 1 are always in the same starting locations.
Level 2 is the full version, having all the features described. At the start of a new game, the objects' locations are always the same.
Level 3 is similar to Game 2, but the initial locations of the objects are randomized, providing a different game each time. The randomization of Game 3 makes its difficulty highly variable, and it is occasionally unsolvable.

The player always begins at the Golden Castle.