War is not a game, games are abstracted, simulated wars. The history of most games, especially team sports trace back to military training or hunting. The entirety of traditional track and field is taken directly from the training of classical era Greek Hoplites.
War comes in two flavors: ritualized and to the knife.
Ritualized warfare is usually fought between the elites of the same culture although sometimes different polities. It has rules. Just read a reference yesterday that noted that between IIRC 1200-1500 in Europe, the number of actual casualties in wars, among nobles at least, the only "people" actually recorded, dropped dramatically. The goal became to capture and ransom the nobles, not kill them. A similar pattern arises whenever a dominant culture is not threatened by either class rebellion or an external alien enemy. That's where you get the whole, "single combat between kings ends the war myth." I say myth because beyond the scale of a couple of Irish clans sometime, it never happened.
There's a "why so serious" class funny story about the first contact between the Japanese Heian nobles(pre-samurai) nobility and the first Mongol reconnaissance in force to land in Japan. The Heian hadn't fought anyone else in centuries if ever so they had elaborate rituals. It started when the highest statist noble advanced ahead of the lines, shouted a challenge to single combat the Mongols didn't understand and then fired a special whistling challenge arrow over the Mongol intentionally not trying to hit anyone.
The Mongols, having a more workmanlike approach to warfare, returned fire with their recurve bows, charged on foot, feigned a retreat which the Japanese fell for, then the Mongols went to work with sword and spear until they couldn't stand up from laughing so hard.
Moral: Know what kind of war you're in. At the height of the age of Chivalry, European elites would simply lie, break truces and butcher peasants that got uppity.
Also, war is only a waste in the corporate/industrial era when economic creativity, utilization of surplus to create more production, is possible. Prior to the corporate/industrial era, productivity was largely fixed and improved only imperceptibly over generations. Wealth meant control of agricultural lands (really not so much the land as the farmers on the land), if you wanted to increase your wealth, you need to steal land and peasants from someone nearby.
This is called the Malthusian-trap. If you want people to fight constantly you stick them in a Malthusian-trap.
In a static, "sustainable" world, war is, except for a tiny minority of individuals, traders, merchants and artisans, the only means of gaining wealth, which means food, and power, which means more food to feed soldiers. Even a pacifist content with their lot cannot escape because they have maintained a defensive force which gets expensive, creating an incentive for war, and an army needs to fight now and then to stay effective so sometimes wars are just bloody training exercises.
Wars were staggering common, everywhere prior to the corporate/industrial revolution. Every polity in every culture that wasn't nearly completely isolated was a garrison state, ruled by a warrior elite we did nothing since toddlerhood but train to kill.
So, if want a kind of ritualized war that's real but not to real you need
- Pretty much a monoculture across the whole field of conflict e.g. a planet.
- A Malthusian zero productivity economy were war is the only means of advancement or improved security.
- A powerful institution, like the medieval Catholic church, that has the moral authority to keep things from getting too out of hand.
- A system like captures and ransoms which lets individuals profit from fighting without having to actually slaughter everyone. Ransoms were often paid in land exchanges if movable wealth was not available.
You could create such a world out of the more extreme versions of environmentalism emerging today, especially the theological version (Gaia worship.)
- Firstly, a world regulatory state task with "protecting the environment" is established. At first, it looks all very scientific and humane.
- But since "the environment" is literally everything in the biosphere and everything every human being does affects "the environment" the regulatory state soon acquires the moral and legal authority to micro-control every choice of every human on the planet. (NOTE: The more real and significant the actual "environmental" problems are, the quicker the regulators gain power and more draconian they have let to act. Could even be an utterly legitimate planet-wide state of emergency requiring de facto martial law for decades.)
- To assist control, they foster a mystic view of nature with superstitions like, "the balance of nature" or "human's rightful place in nature." This lets them establish the moral foundations for a static, "sustainable" Malthusian-trap.
- The regulatory authority evolves into Church governing a worldwide religion. Perhaps an incorruptible AI is actually the "Pope" programmed to maintain some sort of static world order indefinitely.
- High technology especially WMDs are first suppressed and then edited from history. Science, discovery, exploration, art or any other activity that might break the stasis is likewise suppressed and then forgotten.
- But the Church needs enforcers and needs to keep the population distracted and controlled, plus people being people, soon Malthusian wars break out and "Oceania is always at war with Pacifica."
- While allowing the wars, the Church overtly condemns them and maintains a hippy-nature-loving pacifist ideal to the face of the world. This allows wars to become more ritualized and less destructive.
Granted, this is probably more "Game of Thrones" than you wanted but it’s a plausible way to people fight constantly for a long period but not to destructively.
I would point out that the actual scale and destructiveness of wars has been on a long downward slide for the last 500yrs. The ways we have today are frankly pissant compared to the size of the populations involved vs casualties. In the Netherlands war of Independence, for example, the siege of Omstead(sp?) cost 300,000 live in three years. That was just one mid-sized city.
Also, terrorism is HIGHLY ritualized and exist only because we choose to let it. Terrorism relies entirely on mass media to magnify an attack which in a real war e.g. WWII wouldn't even be noticed into a world-shaking event. Everyone has known since the 1960s that you can stop terrorism cold by simply ignoring attacks and censoring any mention of them. Without media and now the internet whipping everyone into a frenzy, no nutjobs would have any incentive to die in an attack knowing they would be ignored and forgotten.
But here we are. We let the Soviet introduce the mythology of Terrorism so we're kind of stuck with it, at least until the terrorists screw up and break the narrative which I think they are close to doing. They don't understand who their friends in the West are.
So, it might be hard to justify spending many resources trying to stop "wars" when they seem to spiral down on their own.