Guests energy level will slowly go down as they walk throughout the zoo. The fifth and final standard for guests is their energy level. It is called the fancy restroom, and it is simply a family restroom, made completely of wood. The fourth and final restroom available in Zoo Tycoon is only available from the Zoo Tycoon: Complete Collection expansion pack. The aquatic restroom is the exact same as the family restroom, only the roof is a turquoise color, and is made of metal. The third restroom is a part of the Zoo Tycoon: Marine Mania expansion pack, and is called the aquatic restroom. It has the exact same design as the small restroom.

A second restroom is the family restroom, which holds about ten people at a time. It is a concrete building with a yellow thatched roof. One is a small restroom, which only holds about four people, and is available at the beginning of the game. There are four kinds of restrooms in Zoo Tycoon. Guests will always need to use the restroom after they're in the zoo for extended periods of time. Just like hunger, if the thirst need gets too high for too many guests, then a red message will appear at the top of the screen that says, 'Guests can't find any place to buy drinks.' Two alternative messages that can appear are 'There are lots of hungry guests.' and 'There are lots of thirsty guests.' The fourth standard is a restroom need. However, instead of using a food stand to make this need go down, they have to use drink stands. If enough guests get very hungry, then a message will appear at the top of the screen in red letters that says, 'Guests can't find any places to buy food.' The third standard is thirst, which is met in a way that is very similar to hunger. If a guest's hunger need isn't met, then their happiness will greatly decrease. When a guest gets hungry, they'll go out to get food from a food stand. This can be changed simply by meeting the other needs of the guests. Guests all have five standards that need to be met: The first is happiness, which is simply a measure of how happy a guest is.

The way to please guests is to meet their standards. This can be done in a plethora of ways, and can be very difficult to do. In Zoo Tycoon, one of the goals is to keep guests happy.

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