Roulette shows the effect of rules more plainly than any other game. A wheel with one green zero keeps about 2.7 percent of every bet, and adding a second zero raises that to about 5.3 percent without changing a single payout. Some tables with one zero return half of an even money bet when the ball lands on zero, which halves the edge on those bets. The layout looks alike in every version, so the number of zeros is worth checking before the first chip.
Blackjack played with sound strategy carries one of the lowest edges in a casino, often under one percent, and the rules decide exactly where it lands. A natural paid at six to five instead of three to two adds more than a full percentage point on its own. Fewer decks, the right to double after splitting and an offer of surrender each trim the edge slightly. A player who guesses instead of following basic strategy pays several times the published figure.
The expected cost of play is the edge applied to the total amount staked, and the pace of a game decides how fast that total grows. A fast online table can deal several times more rounds per hour than a busy physical one, so a small edge applied quickly can cost more than a larger edge applied slowly. A simple formula, the average stake times the rounds per hour times the edge, gives a fair estimate of what an hour at a given table is going to cost.