I had a concept for this. They are what I would call Conflict Worlds. Planets engineered solely for warring factions/nations. Basically, they're specialized planets with just about any biome you can think of (more tactical use, than resourceful civilian use), planted away from worlds of origin, to keep damage within the arena/planet. Homeworlds remain safe and intact, and civilians are safe in their ignorant bubbles of reality.
Optionally, these wars can be broadcast like a tournament of the ages kind of deal. Real war and such, but you can place bets on them and such, and even make a quick buck by joining a merc squad to help pad numbers to make battles fair. Oddly enough, Planetside comes to mind with this concept, amplified with Unreal Tournament.
And of course, my Conflict World concept has to be a large enough world to support numerous wars simultaneously; so basically, an Earth-like world the size of Jupiter. Keep nuclear wars literally worlds apart from one another on each pangea-sized continent (literally an Earth's-distance (circumference (24901.461 miles or 40075.017 km)) away from one another). Literal world wars can be held on their own continent, and be broadcast live to the audience via drones (painted like refs with a specialized IFF signal encoded to not be a target for any nation/faction; destruction of one results in a warning, second-offense, you lose a structure, as sanctioned by the war commission, and if repeated-offender,
DFA to the sector abusing policy; if abused as a tactic (small group taking out refs to wipe out the bigger enemy with them), then armed intervention by a 3rd party will occur until the war conditions are fair again).
There have yet to be a proper political battleground like this. May be a challenge to herd sheep into a Political Conflict World. The Internet may qualify, I guess.