You are competing for oil!

In a few moments, you will see a large lot of land. Under the sand, there may be oil reservoirs. Some reservoirs are deeper or wider than others. You cannot know where reservoirs lie just by looking at the sand. The only way to find oil is by drilling. And you will have the opportunity to drill once per round for 15 rounds. Your success in finding oil will determine your score.

Each round lasts 20 seconds. When the round begins, choose one spot for drilling and click "drill" within 20 seconds. Then, you will see the amount of oil you found in that spot. The amount is indicated by a colored square and a corresponding bar on the left side of the screen. A higher bar indicates that you recovered more oil.

If there are oil reservoirs under the sand, their locations and sizes are determined before the game begins. During the game, the locations and the sizes are not affected by anyone's actions and do not change.

You may not be the only one drilling. You may have competitors, and they are also drilling for oil. If competitors are present, you will be able to see where they drill, but not how much oil they find.

If you choose to drill in the exact same point as a competitor did, you will find the same amount of oil as the competitor.

After everybody has chosen a drilling spot or 20 seconds have passed, the round will end and everybody will move to the next round. If you have not made a decision within 20 seconds, then you will find no oil in that round.

The game may repeat several times. Whenever a new game begins, the locations and sizes of the oil reservoirs, if any, may shift. Also, your competitors, if any, may change.

Every game will have one winner: the competitor who found the most oil.

This is an example of the game interface.

This is an example of how oil reservoirs may be laying under the sand. You and your competitors can find the reservoirs only by drilling. You will never see where reservoirs are unless you happen to drill into them.

Please enter your first name. Your name will be visible to the other competitors.

Before you begin the game, please answer the following questions.

In this game, you're drilling for --select-- diamonds coal oil gold silver

When competitors drill, you --select-- can can not see where they drill and you --select-- can can not see how much oil they found, if any.

How many seconds do you have to make a decision? --select-- 5 10 15 20 22.5

The game advances to the next round after
at least two competitors found oil
everybody chose a drilling point
everybody chose a drilling point or 15 seconds have passed
at least 15 seconds have passed
at least one competitor found oil

Which of these statements is true?
The location and size of oil reservoirs is fixed throughout the game.
The location of oil reservoirs is fixed but the size may change during the game.
The size of oil reservoirs is fixed but the location may change during the game.
The size and location of oil reservoirs may change during the game.
The size and location of oil reservoirs can be deduced from the color of the sand.