Answer:

war

Answer	Crossword Clue
WAR	Conflict
WAR	Endless card game
WAR	Hell, to Sherman

WAR	Trojan, for one
WAR	Old Maid alternative
WAR	All-out fight
WAR	Hostile encounter
WAR	It's hell
WAR	Two-player card game
WAR	Common video game milieu
WAR	Peace, per Big Brother

WAR	Card game that is (aptly) arbitrary and seemingly neverending
WAR	Kids' card game
WAR	1914 headline
WAR	Hostilities
WAR	Game of sheer luck
WAR	Series of skirmishes
WAR	Combat
WAR	Ares's realm

WAR	Simple card game
WAR	Affair of Ares
WAR	Strategy-free card game
WAR	Theater goings-on
WAR	One of the Four Horsemen
WAR	Open hostilities
WAR	Sherman's "hell"
WAR	Kids' card game for two

WAR	"Politics with bloodshed": Mao Zedong
WAR	Sun Tzu's area of expertise
WAR	Cabinet department that split in 1947
WAR	Campaigner's contest (or the start of a 1930s movie actor's split personality)
WAR	Card game requiring no skill
WAR	Child's card game
WAR	Highest-card-wins game
WAR	".. and Peace"

WAR	Kind of game or story
WAR	Serious conflict
WAR	Struggle
WAR	Armed conflict
WAR	Basic card game