Can you tell me what does it mean? Simple quote from a book, but very confusing

Hello Everybody

I am reading a book about Game Theory. The author was talking about when gas stations compete to get the best place and then, they ended clustering together in the same place.

He wrote
" Nevertheless, there is a simple game about location competition that provides valuable insight. While the game involves only a few rules, it illustrates how businesses might compete on location and end up clustering together. The game also has an application to political science in the strategy for campaigning in elections. The following game is based on a model described in the 1929 paper " Stability in competition"

What does he mean by a few rules !?

Thank you very much

He means that the game is not complex, there are only a small number of rules ( perhaps just 3 or 4 or 5) you need to follow.
Cheers. B

Actors or players in game theory are supposed to behave according to a few rules.

The prisoner’s dilemma is very famous.
“The prisoner’s dilemma is a canonical example of a game analyzed in game theory that shows why two purely ‘rational’ individuals might not cooperate, even if it appears that it is in their best interests to do so.”—Wikipedia

The Prisoner’s Dilemma Explained
Check out this video on YouTube: