What is return to player?
The percentage of all money wagered that a game pays back to players over the long run; the house edge is the remainder.
Return to player diagram example
Return to player, or RTP, is the share of all wagered money that a game is designed to pay back to players over a very large number of plays. An RTP of 96% means 4 of every 100 wagered are kept by the operator. It matters because it tells designers and players the long-run payout level.
How it works
RTP = total expected payouts ÷ total amount wagered, and house edge = 1 − RTP. It is an average over a huge number of plays, not a promise about any single session. Individual results vary a great deal, especially in games with rare large wins, so a player can win big or lose everything with the same RTP.
Designers balance RTP against variance. Two games can share a 96% RTP while one pays small wins often and the other pays large wins rarely. The first feels steady, the second feels exciting but risky. Because the payout is built from many parts, such as base wins and bonus rounds, the RTP is the sum of each part's contribution.
Example
Say a game has three outcomes per 1 bet: lose with probability 0.80, win 2 with probability 0.15, and win 10 with probability 0.05. Expected payout is 0.15 × 2 + 0.05 × 10 = 0.30 + 0.50 = 0.80. RTP is 80%, so this toy game keeps 20%. Raising the big prize to 18 gives 0.30 + 0.90 = 1.20, an RTP of 120%, which loses money for the operator. These are illustrative numbers.
How to model it in Machinations
Use a Source of wagers into a Gate that splits plays by outcome probability, and Converters paying each prize. A Register computes RTP as total paid divided by total wagered. Set probabilities and prizes as Levers. Play many times at once and chart the Register to see it settle near the designed value, and reduce the number of plays to see it wobble.
See return to player in a system you can Play
Build the rules in a Machinations diagram, change a value and Play it to watch how the system responds.