Zoo Keeper is an arcade game created by Taito Corporation and released in 1982. In the game's storyline, the player's character, named Zeke, is a zookeeper whose girlfriend, Zelda, has been kidnapped by a malicious monkey. To distract Zeke, the monkey has unlocked the cages in the zoo, allowing the animals to escape. The player must control Zeke to run, jump, build walls, and collect bonus items in an effort to recapture and contain the animals before finally rescuing Zelda.
Zoo Keeper has three different types of stages: a main stage and two bonus stages. In each stage, the player's score and the number of lives that Zeke has left are displayed in boxes at the top of the screen. Two players can play the game in alternating turns. The arcade cabinet controls consisted of a 4-way joystick, a button on each side of the cabinet for jumping (one per player), and one-player and two-player start buttons on the front.
Main Stage: Contain the Escaping Animals
In the first type of stage, Zeke moves and jumps along a rectangular perimeter surrounding a cage in the center of the screen, which is unlocked and thus allowing animals inside to escape. Zeke's orientation changes as he walks around the perimeter (at the bottom of the rectangle he appears to be upside-down), and players must adjust their joystick movements as he moves around corners. As he walks, he quickly builds a brick wall under his feet that is intended to keep the animals from moving outside the perimeter. The wall he builds becomes thicker as he walks around the same area multiple times, but the animals are also breaking the wall from the inside as they try to escape, so the stage is a constant fight between Zeke and the animals to build up and tear down the perimeter wall. The first two main stages begin with a thin wall already in place, but after that the wall must be built from scratch. Zeke builds thicker walls as the game progresses.
If an animal escapes from the perimeter, it roams freely around the perimeter just like Zeke, who must then avoid the animal by running in the opposite direction or jumping over it. If Zeke touches an animal (without using the zookeeper's net), he will lose a life and have to start over again, although any walls currently in place will still remain. Jumping over animals earns points, and the number of points increases exponentially with the number of animals under Zeke during the jump. Zeke's jump distance is fairly long, he can jump around corners, and he can change directions in mid-air. Therefore, part of the stage's point-earning strategy is to jump over as many animals as possible in a single jump. A musical sound is played when Zeke jumps over animals (very similar to the music played at a baseball game before fans chant "Charge!"), and the pitch of the music increases depending on how many animals were jumped.
While Zeke is building walls and jumping over animals, a timer at the top of the screen is counting down to the end of the stage. The animation of the timer graphic is analogous to a fuse like one would see attached to a stick of dynamite. As this fuse "burns" from left to right, the burning end crosses over a series of four items along the fuse. When an item is burned by the timer fuse, a distinct sound is heard, the item appears on the perimeter (in a pre-determined position for the stage), and Zeke can then grab the item by moving over it. The item disappears if the fuse moves over to the next item before Zeke can grab it.
There are two types of items: bonus items and the zookeeper's net. The player is awarded a set number of points for the first item that is grabbed, and each additional item collected will award double the points of the previous item. The zookeeper's net will also award points just like a bonus item, but additionally the screen will turn blue and Zeke will briefly be able to use the net to recapture animals that are roaming the perimeter by touching them with the net to force them back into their cage. The net only moves the animals back inside the perimeter, the cage is still unlocked and Zeke must continue to maintain the wall to keep the animals contained.
The stage is over when the timer fuse burns to the "END" box in the upper righthand corner (the box "explodes" and a "gong" sound is played). At the end of the stage, the player receives bonus points for each animal that was within the perimeter when the time expired. The number of points for each animal depends on the type of animal (bonus points for lions also increase with harder stages). A distinct sound is played for each animal type as they are inventoried at the end of the stage. A laughing sound is heard if no animals were contained.
The escaping animals stages are the most common stages in the game, with the other stage types interspersed between them. When the game is first started, instructions are shown for how to play this type of stage, but not for the other stages. The number, diversity, and ferocity of the animals increases with each new stage. Each stage has its own type of bonus items and item distribution along the fuse, meaning that the zookeeper's net may appear early or late in the stage. Additionally, the fuse itself takes longer to burn to the end in later stages, making animal containment and survival more difficult. The color borders around the stages also begin to flash after the first lion stage. Zelda does not appear in these stages.
Bonus Stage: Rescue Zelda from the Monkey
In the second type of stage, Zelda is tied to a palm tree on a stationary platform at the top of the screen, yelling "Save Me!". A monkey hangs by its tail from the top of the palm tree, picking coconuts from the tree and hurling them to bounce around the moving platforms below. Zeke starts on the bottommost platform and must jump up and across the platforms to reach Zelda, avoiding the coconuts as he ascends. Many elements of this stage have striking similarities to stages in the arcade game Donkey Kong, which was very popular when Zoo Keeper was released.
The moving platforms move horizontally in both directions across the screen. Platforms move in and out of the screen viewing area, but Zeke can not move out of the screen area, so he must constantly move and jump to avoid falling. If Zeke falls below the bottommost platform, he will lose a life. Points are earned every time Zeke jumps to another platform level, even if he jumps down and back up again, and the number of points for each level doubles as he gets closer to the top. Moving platforms sometimes have various bonus items that Zeke can pick up for extra points (four times the value of the platform they are on). Each row of platforms has its own type of bonus items, and items closer to the top give the most points. Some cabinets also offered a free game as a bonus item in this stage. However, the longer Zeke spends getting bonus items, the more coconuts the monkey will have time to throw. Zeke will lose a life if he touches a coconut or falls off the bottom of the screen (Zelda will say "Oh No!"), and he will have to start over again. Rescuing Zelda awards double the value of the topmost platform.
This rescue stage first appears after the second escaping animals stage. The monkey becomes more aggressive in later stages, throwing many more coconuts in series, but the bonus items are also more valuable. The platforms themselves are invisible in later stages, and the player can only tell they are there by where the coconuts bounce and the bonus items. Gameplay in this stage is very different from the escaping animals stages. There is no zookeeper's net or any offensive weapon against the coconuts, no animals in this stage other than the monkey, there is no timer, and Zeke is always facing upright and no walls are built. This stage is analogous to reward/bonus stages seen in other video games, an intermission from the main action. Zeke receives bonus points when he rescues Zelda, who then says "My Hero!" Rescue bonus points are doubled each time Zeke rescues Zelda from the monkey.
Bonus Stage: Ride the Escalators
The third type of stage finds Zelda on a platform at the top of a series of escalators and poses the question "Can you win a bonus keeper?". At the bottom of each escalator is an unlocked cage filled with animals of various types which charge out away from the escalator toward Zeke. Zeke must jump over the animals and the cages to ascend the escalators to get to Zelda. This is challenging because while players will be familiar with how to jump over the animals, they may have trouble anticipating the pattern in which they emerge from the cages. Furthermore, the cages themselves are taller than the animals and electrically charged, so jumping over them requires a correct starting position. If Zeke does not clear the cage, a loud noise is heard and he is bounced backwards (a reaction to the electricity around the cage). Each stage has at least two escalators, alternately ending on the right and left sides of the screen on the next platform.
The first escalator stage is after the second time Zeke rescues Zelda from the monkey. It is another intermission/bonus stage and, aside from avoiding the animals, has no other elements from the main escaping animals stages. If Zeke rescues Zelda, the player receives a bonus life and Zelda also has a romantic exchange with Zeke (she showers him with kisses the first time, but in subsequent escalator stages a "curtain" is pulled down over them, and players are left to their imaginations). If Zeke touches the animals, Zelda will say "Oh No!", Zeke will curse "#$%&*@!!!!", and he will have to try again.
Players earn points in the game by containing animals, jumping over animals, and collecting bonus items.
Aside from the monkey, which really doesn't count as one of the main escaping animals, there are six types of animals in Zoo Keeper, shown here in order of appearance and increasing difficulty, along with points rewarded if they are contained:
- Elephant (250 points)
- Snake (500 points)
- Camel (1,000 points)
- Rhinoceros (2,000 points)
- Moose (4,000 points)
- Lion (30,000 points to start, up to 60,000 points for later levels)
Jumping Over Animals
Players can earn extra points by jumping over animals in the main stages and escalator stages. The number of animals that Zeke jumps over determines the bonus. The veracity of the point system should be controlled - one gaming expert claims that jumping over a rhinoceros is actually worth 4000 points, while jumping over a moose is only awarded with 2000.
Collecting Bonus Items
These items can be picked up in the escaping animals stages or the coconut monkey rescue stages. They are listed in order of first appearance in the main stages and bottom-to-top in the bonus stages, along with their initial point values on the main stages:
- Root beer (120 points)
- Four-leaf clover (250 points)
- Sundae (500 points)
- Watermelon (1,000 points)
- Strawberry (2,000 points)
- Trophy (3,000 points)
- Money (5,000 points)
- Pot of gold (7,500 points)
After a player presses the start button, the gameplay proceeds in the following order:
- An introduction screen (showing how to play the main stages of the game).
- Main Stage #1: Elephants only, with Root Beer bonus items. The wall is initially two bricks thick.
- Main Stage #2: Snakes added, with Four-leaf Clover bonus items. The wall is initially one brick thick.
- Monkey Stage: Bonus items from Root Beer up to Strawberries.
- Main Stage #3: Camels added, with Sundae bonus items. There are no initial walls from now on.
- Main Stage #4: Rhinoceroses added, with Watermelon bonus items.
- Monkey Stage: Bonus items from Four-leaf Clovers to Trophies.
- Escalator Stage: Two escalators.
- Main Stage #5: Moose added, with Strawberry bonus items.
- A notification screen that tells the player to try to capture the Lions in the next stage.
- Main Stage #6: Lions added, with Trophy bonus items. Captured Lions are worth 30,000 points.
- Monkey Stage: Bonus items from Sundaes to Money.
- Escalator Stage: Three escalators.
- Main Stage #7: No new animals but increased difficulty, with Money bonus items. Captured Lions are worth 40,000 points. Sides of the screen flash beginning with this stage.
- Main Stage #8: Even more difficult, with Pot of Gold bonus items. Captured Lions are worth 50,000 points.
- Monkey Stage: Bonus items from Watermelons to Pots of Gold.
- Escalator Stage: Four escalators.
- There are additional, more challenging stages.
When all of Zeke's lives are gone, the game is over. As with other typical arcade games, if a player's score is high enough, they may enter their initials to record their score on the machine.