According to Wikipedia, "Game theory is the study of mathematical models of strategic interactions among rational agents."
Game theory has only limited usefulness for social scientists because society consists of many games, not just one, and these games interact with each other. The world is much more complicated than any single game.
Decades ago, I tried to make chess more like society, converting it into a more complicated game than it already is. On an ocean liner between Honolulu and San Francisco, I was accosted by guy who wanted to play chess. When I informed him that I was not a strong player, he claimed he wasn't either. He lied.
He clobbered me, having memorized standard approaches to chess moves. Mortified, I invented a chess version to force people like him to live by their wits, like I have to.
Flexichess begins like regular chess. But instead of moving a piece players can, within a few limits, change a rule, altering the whole balance of forces on the chessboard. No one can predict how rules will be changed, throwing rascals like my steamship companion off balance.
Later, I converted Flexichess into a team sport, Perplexichess. Teams consisting of 7 players play Flexichess on seven boards. On top of this a team's eighth member—a grand strategist—can move pieces to the same location on another board if it is unoccupied, without taking turns with the other grand strategist!. The grand strategist's goal is to win a majority of the boards.
The main game many people play, especially in poor countries or among poorer people in rich countries, simply seeks physical survival.
Board players, playing Flexichess rationally, may be defeated because their team's grand strategist sacrificed their board by moving key pieces to a board where they were worth more.
Since it has many games going on simultaneously at two different levels, Perplexichess is very complicated. But it is still much less complicated than human societies are.
The world is made up of a vast number of different "games" simultaneously played by seven billion people. The main game many people play, especially in poor countries or among poorer people in rich countries, simply seeks physical survival.
Other people may be playing romantic games. And there are an endless number of games played by individuals in corporations, labor unions, churches, schools and universities, interest groups, hospitals, and charitable organizations.
Most individuals are playing several different games.
At a still higher level we find games played by politicians seeking appointment or election to high government positions.
The winners in these political games find themselves in games at a still higher level, seeking to protect themselves from challengers. While they remain in power, many of them may seek to advantage their own glory and their government at the expense of others, sometimes even getting their countries into wars.
As in Perplexichess, the games played at a higher level of society can throw the games of people playing at a lower level into total chaos. For example, a student planning to become a scientist might be drafted to fight a war in some country with which he (or she, in some countries) has no connection, concern, or knowledge.
On 9-11 many financial executives working in the Twin Towers found their professional games, and their lives, undone by a game played by the fanatics who crashed hijacked airliners into their buildings.
Lower level games can also confound those playing higher level games. National leaders attempting to minimize injuries caused by Covid have been frustrated by games played by governors, political opportunists, and foreign enemies who injected divisive social media memes into our society.
No wonder it is nearly impossible to predict what is going to happen next! And the complexity caused by the interactions of multiple games also makes it difficult to understand what has already gone on, creating opportunities for crazy conspiracy theories to catch on.
A conspiracy theory can be simple and consistent, whereas reality is often messy.