Cowboys and Indians
Long before the days when kids quarantined their fantasy gun violence inside their homes and over the internet through online first person shooters with people they've never even met, they'd have to use the graphics processor of the human imagination. Yup, those were the good old days, back when kids could buy dynamite from their local convenience store and when mom and dad could get a prescription for opium, heroin, cocaine, and methamphetamine from their doctor. It was an age before political correctness made glorifying genocide taboo, yet at the same time pretending to be Nazis gave dad too many flash backs of liberating Europe and dressing up as black clad ninjas awoke too many memories of the Japanese shadow warriors sneaking through the moonless darkness of the jungles of the pacific islands, hacking through vines and limbs with an officer's samurai sword. Cops and Robbers reminded grandpa too much of his days as a rum runner firing out the window of a Model T with a Thompson submachine gun, and playing Union versus Confederacy required that you have an African American friend to liberate from plantation slavery, and that kind of made you wonder why your friend still had to use a different bathroom and drinking fountain than you. Playing red shirts versus colonists took forever to load the muskets with a powder horn, and no one wanted to march in a line and and get shot at, while pirates not only had to reload their flintlock pistols after every shot but had to do it with an eye patch, a peg leg, a hook for a hand, and no depth perception, so naturally there was really only one form of fantasy gun violence for kids to play, Cowboys versus Indians.
Gameplay would normally begin by killing off 90% of the Indians with smallpox before the first colony was even set up. Unlike Native Americans, Injuns were incapable of adapting new technologies like guns and horses, or interbreeding to acquire immunity or discovering smallpox vaccination from a traveling Chinese Ottoman or Indian explorer who traveled to Mexico is against the rules. If you want to play science fiction it has to involve aliens or robots, no alternate timelines or weird medical stuff allowed Lady Mary Montagu, go read your socialist manifestos by H.G. Wells somewhere else you commie, this here's supposed to be Manifest Destiny. Next thing you know you're going to try and invent a system of glass or metal mirrors that blinds the cowboys by focusing light from the sun, a camp fire, or a lantern, into their eyes. Maybe focus the light onto the dry prairie grass, catching it on fire or melt the snow uphill starting an avalanche, like you were defrosting the deck of a viking ship with a magical rock crystal. It also comes in handy for lighting tobacco pipes, according to 50's doctors cigarettes are an excellent treatment for childhood asthma.
As soon as you've constructed a colony, the Indians have to help all the pilgrim's moms cook Thanksgiving dinner by teaching them how to plant corn, giving you the energy you'll need for betraying their misplaced faith in your humanity, suckers. As soon as the rail road or school bus has arrived, cowboys get to steal the Indian's buffalo in the form of their school lunches and winter coats. After play progresses, the Indians are forced off to increasingly distant neighborhoods they've never actually been to before, monitored by an Indian Agent who controls their access to essential supplies from the grocery store, until eventually being forced out of town entirely after it's discovered there are valuable natural resources like uranium or oil reserves underneath their reservations. Contrary to popular belief girls can also take part in Cowboys and Indians, as they take up the role of abusive nuns and teachers playing residential school. At this point the game switches from guns to cards as the remaining Indians become Blackjack dealers at a casino. The name of the game is now changed from Cowboys and Indians to Cowboys and Viet Cong and later Cowboys and Iraq/Taliban insurgency; as Indians are predisposed to being bad asses with disproportionately higher rates of military service than any other ethnic group, they are are now allowed to be cowboys, someone else now the oppressed colonized people.
In other regions the beloved children's game is known as Europe versus Africa, English versus actual Indians, Christians versus Pagans and Communists versus the mentally ill.