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MyGURPS - Simulating Slot Machines with a d6

Simulating Slot Machines with a d6

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Slot machines have been around since the end of the 19th century, and while modern versions may add digital processors and animated graphics, the basics of a "pull" remain the same: put in money, yank the lever (or click the button), and see whether the symbols line up in a pleasing manner.

To simulate this in an RPG, all you'll need is a d6. You're going to roll it multiple times (at least, if you're lucky!), but resist the temptation to just grab a bunch of d6 and throw them at once. There is a huge difference in probability between "rolling three 6s in a row" and "of the seven dice I just tossed, three were 6s"!

The Rules

Pick up a d6 and roll it according to the following instructions. The tension of seeing how you roll will be similar to the tension of watching the slot symbols fall into place.

The d6 roll "succeeds" either on a 6 or on a 5 or 6, as noted in the table. Every time you succeed, roll again and try for another success; as soon as you fail, stop and total your successes. (If your first d6 roll is a 1-5, the slot machine pays nothing.)

Example: On the Classic machine below, you roll a 6 (success), then a 6 (success), then a 4 (failure). The slot machine comes up with two Jokers.

Gambling Skill: Slots is a purely random game; as such, Gambling skill does not come into play at all . . . with one exception. Some early-model manual slots gave you control over when the reels began to lock, letting a savvy player try to line up a good result. In such a case, successful use of Gambling skill lets you count 5 or 6 as success on the first roll (only). A critical success, raise, etc. lets you do so on the first two rolls.

Luck: Few things are as luck-based as slot machines. As such, any ability or meta-game token which would normally let the gambler reroll a dice roll can instead be used to make one pull "lucky," rerolling 1s (once per 1).

Typical Slot Machine

This table offers two popular slot machine styles, classic (card suits) and modern. It is intentional that Jokers and Cherries do not match each other; the machines are weighted differently. Due to their iconic nature, three-reel slots are assumed here, but other models use the same rules (just change the descriptors).

"Payout" is a multiplier of whatever it costs to play the slots. For example, if you're playing nickel slots, getting three Spades translates to $50 (1,000 x $0.05) for a net gain of $49.95.

SuccessesClassic StyleModern StylePayout
For the rolls below, a 6 succeeds
1One JokerOne Cherryx2
2Two JokersTwo Cherriesx5
3Three ClubsThree Cherriesx25
For the rolls below, a 5 or 6 succeeds
4Three DiamondsThree Bellsx50
5Three HeartsThree $sx250
6Three SpadesThree 7sx1,000
7Three JokersThree BARsx5,000

Technical Details: This is a generous slot machine, with 0.994 payout, simply because that's more fun. Payout value (odds x payout) for the seven possibilities are 0.320, 0.104, 0.059, 0.040, 0.071, 0.114, and 0.286. Reduce the highest payout to x4,000 for more realism (0.937).

"High Roller" Machine

This is a modern, digital machine (never manual!) with five virtual reels. In most places, it costs $10 per pull, allowing it to advertise a literal "million dollar jackpot." It has a wide variety of symbols, but the one that pays out well is the diamond. Other symbols pay decently on a triple, and there's modest reward simply for avoiding "X" symbols.

The odds of hitting the higher-level payouts are, of course, extremely slim; the d6 only ever succeeds on a 6, even at higher levels.

For all rolls below, a 6 succeeds
1No Xsx2
2One Diamondx5
3Two Diamondsx25
4Triple Non-Diamondsx100
5Three Diamondsx150
6Four Diamondsx5,000
7Five Diamondsx100,000

Technical Details: Also generous at 0.994 with payout values 0.267, 0.111, 0.093, 0.062, 0.016, 0.089, and 0.357. For more realism (0.940) without invalidating the marketing, reduce x5 to x3 and x25 to x20.

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