Reading "How keno works?" starts with the family it belongs to. Every casino floor carries a few games that are neither cards dealt to a hand nor a wheel with a ball in it. Keno, bingo and scratch cards all work by matching numbers or symbols already decided somewhere else, and casino war sits beside them as the shortest game in the building. They share a shape: the player commits first, and the result arrives in one step.
Keno asks for a handful of numbers from a field of eighty. Twenty are drawn, and the payout depends on how many of the picks appear among them and on how many were picked in the first place. That second half surprises people: matching four of five is a different prize from matching four of eight, and each spot count has its own column on the pay table. The table is the game, and two venues running the same draw may pay quite differently.
Bingo replaces the pick with a printed card and the draw with a caller. Numbers come out one at a time and each player marks a card against them until a pattern completes — a line, two lines, or the full card. A ninety ball game and a seventy five ball game differ in the size of the field and in the patterns that count, which is why the rules sheet matters more than it looks.
A caller draws numbers one at a time, and each player marks them on a printed card until a winning pattern completes.
When both cards match in rank, the player chooses to surrender half the stake or raise and go to war; the house draws most of its margin from ties.
Every choice comes before the round: how many keno spots to take, which card to buy, or whether to go to war, since the draw itself allows no strategy.
The table of prizes still remaining in a run shows what is actually left to win, which says more than the overall odds on the back.
Common winning patterns are a single line, two lines, or the whole card, known as a full house, with the rules sheet naming which ones count.
The two games use fields of different sizes and count different patterns as wins, which is why the rules sheet for each matters more than it seems.