Dice Arena

A casino console in Rust — zero external crates, including its own PRNG and its own raw-terminal input (direct termios(3) FFI, no crossterm). Twenty-four tables across four rooms, every one of them animated, every one able to run itself with nobody watching — a whole casino that keeps running on its own thread while you play something else, and an operations centre to watch the lot of it from.

cargo run --release

Controls

Every screen in the app is driven by single keypresses — there is no typing a letter and pressing Enter. The terminal is put into raw, no-echo mode on launch, so the instant you press a key it acts:

• Menus and in-game choices: press the bracketed key shown, e.g. [R]oll, [1] Pig, [Y]es — the action fires immediately.
• Numeric pickers (a target score, a chip stake): ↑/→ and ↓/← step the value, digits type an exact number, and any preset keys shown (like [M] for all-in) jump straight there. Enter confirms, Esc cancels — these are the only two places Enter is used, since there's no way to know a typed number is "done" without a terminator.
• Anywhere a name is typed (yours, a second human player's), type and press Enter to confirm.
• Ctrl+C leaves the table/menu you're in immediately and cleanly closes the app, saving as it goes.
• Crash is the one table where a key matters during the animation: C cashes out mid-climb. Everything else settles between frames.
• On any idle screen, Q returns you to the floor.

The whole app runs in the terminal's alternate screen buffer, so nothing scrolls into your shell's history — every screen is a hard clear-and-redraw, and your prompt looks exactly as it did before you ran it once you quit.

The floor

Two dozen tables will not fit on one readable menu, so the floor is grouped the way a real one is. The main menu opens four rooms, plus the idle screens, the Store, your Stats, the Casino's own books, the Rules — and [D], the casino's operations centre.

Dice tables

Pig	Press-your-luck race to a target score. 2–6 players, any mix of humans and bots, classic (1d6) or two-dice variant (snake eyes wipes your score, doubles pay double).
Yahtzee	Full 13-category scorecard, three rolls a turn with dice holding (press 1-5 to toggle a hold, R to reroll, S to stand), upper-section 63/35 bonus, 100-point bonus Yahtzees. 1–4 players, hot-seat or vs. AI.
Luck Bet	Eight dice named A–H. Up to three players each back a letter and the face they think it lands on. A hit pays 5:1 (6:1 with a VIP pass); a miss loses the stake and rakes a fifth of it into a carried-over jackpot. Hit your number while three or more dice show it and you sweep the jackpot too.
Luck Bet: Turbo	The identical game, hands-free. One key spins the table at 20 frames a second for three seconds before it settles; bets repeat automatically.
Chuck-a-Luck	Three-dice wagering. Bet a face (1:1/2:1/3:1 by how many show it), HIGH/LOW at evens, or any triple at 30:1.
Tournament	Chip buy-in, single-elimination Pig bracket (4 or 8 entrants, three tiers). Your matches are played out, the rest of the bracket is simulated. Champion takes 70% of the pool, runner-up 30%.
Dice Lab	Roll any NdM+K (3d6, d20, 4d10+2), plot a distribution with sim 2d6 50000, and pin the RNG with seed 42. The one screen that still takes typed text — there's no sensible key for an arbitrary expression.
Ultra Casino Dice	An unattended spectacle table — 12 dice, 8 computer players, 10 rounds, zero input required. Every round each seat backs a letter and calls a face, the table spins for a full 7 seconds, and whoever called it right splits the pot — losers' stakes are exactly what winners collect, with one exception: a round nobody calls right pays its whole pot to the house. Seats stay or cash out between rounds, and anyone who leaves is replaced. Every round and every session lands in the History screen.

Card tables

All six deal from one shared deck, shoe and set of hand rankings (src/games/cards.rs).

Blackjack	Heads-up against the dealer with a real 52-card shoe. Hit, stand, or double down; dealer stands on all 17s; blackjack pays 3:2.
Baccarat	Back the player, the banker or the tie, then watch a hand nobody makes a decision in — the third-card rules are fixed, and they're the real ones. Player and banker pay 1:1, the banker less a 5% commission; the tie pays 8:1 and pushes the other two.
Video Poker	Jacks or better. Five cards, hold any of them, draw once. A pair only pays from jacks up; from there it climbs to a royal flush at 800:1.
Three Card Poker	Ante, look at three cards, then fold or match your ante to play on. The dealer needs queen high to play at all — when they can't, your ante pays and the play bet comes back. A straight, trips or straight flush pays an ante bonus win or lose. In the three-card game a straight beats a flush.
Casino War	High card wins, even money. On a tie, surrender for half your ante or go to war: match it, burn three, deal again. Win the war and the raise pays even money while the ante pushes; tie again and the raise pays 2:1.
Hi-Lo	Call the next card higher or lower. Every call is priced off its true odds less a small margin, so calling higher on a two is nearly free and calling higher on a king pays richly. Cash out whenever — one wrong call takes the lot.

The wheels

Roulette	Single-zero wheel. Straight-up numbers pay 35:1; red/black, odd/even, high/low pay evens; the three dozens pay 2:1.
Big Six	The money wheel: 54 segments running past a fixed pointer, decelerating into their stop. Back the 1 (24 segments, 1:1) through to the joker or the house star (one segment each, 40:1). The landing segment is drawn first and the scroll is worked backwards from it, so what you watch is genuinely what you get.

The arcade

Slots	Three weighted reels stopping left to right on one payline. The reels are real strips — each symbol appears as many times as its weight — so the odds are visible in the code rather than hidden in a constant. Three of a kind pays 8x to 120x; loose sevens pay on their own.
Keno	Cover 1–10 spots on an eighty-number board; twenty balls come out one at a time. Cover one and a single hit pays 3.7x; cover ten and you need five before anything pays — but all ten pays 250,000x. Every board size returns the same 90–93%, checked against the exact hypergeometric odds.
Bingo	A 75-ball card with a free centre. Forty balls are called and the payout is on how fast your first line lands: 30x by ball 15, down to your stake back by ball 40. Flat-rate bingo would hand the building over — a line inside forty balls turns up nearly half the time.
Plinko	Drop a ball through twelve rows of pegs into thirteen slots. Low, medium and high risk change how sharply the prizes climb toward the edges — up to 220x — but all three return the same share of your stake.
Mines	Choose how many mines hide under twenty-five tiles, then turn them over one at a time. Each safe tile raises the multiplier by the true odds of having got that far. Cash out whenever; find a mine and the round is gone.
Crash	A multiplier climbs from 1.00x and stops dead at a point drawn before the round starts. Press C to take the money first. The chance of surviving to any multiplier is 0.99 divided by it.
Scratch Cards	Nine panels, three of a kind pays. The prize is decided when the card is pressed and the panels are laid out to show it — exactly how a real scratch card works, and why the return to player is an exact number rather than an estimate.
Horse Racing	Six runners at fixed odds from 2:1 to 20:1. The odds come first and each runner's chance is derived from them, so every horse returns the same share of your stake. The winner is drawn before the tapes go up and the race is run to it.

Store

Exchange in-game dollars for chips (10 per $1) and back (12 chips per $1), and buy reroll tokens, insurance chits, lucky charms, a VIP pass or a gold dice skin.

The roll

Every dice reveal in the app plays the same house animation: ten frames of tumbling values over roughly a second, easing from a quick flicker to a settle, before landing on the real, already-determined result. Ultra Casino Dice's table spins to its own longer rhythm — 20 frames a second for a full 7 seconds. Every other table has its own: reels stop left to right, the money wheel decelerates into its pointer, a plinko ball accelerates as it falls, keno balls speed up as the board fills, and a crash curve tightens exactly as the decision gets harder.

Nothing is decorative. Where an outcome is drawn before the animation runs — the wheel's segment, the race winner — the animation is worked backwards from that result so what you watch is what you get.

Dice and card sizing

Faces draw at the largest of three sizes that fits the live terminal: 27×15 for a die and 21×15 for a card, exactly three times the original 9×5 and 7×5, with a middle step between. Nothing in a game picks a size — the renderers measure the window and take the biggest that fits, so Chuck-a-Luck's three dice fill the screen while Ultra Casino Dice's twelve fall back gracefully on the very same terminal. A big card fills its face with its suit drawn as block art.

The casino

[A] Start Casino opens a floor that runs itself. Tables deal, patrons buy in and cash out, and the books move — on a real background thread, entirely independently of whatever screen you happen to be looking at.

• Pick a floor — a quiet night, a busy floor, one of everything, or all fifty-one tables at once. Open more at any time.
• The overview lists every running table with its seats, round, status, take and last result, with what is going on in the building tonight above it and a strip of recent goings-on below. Move with J/K, watch one with W, pause with P, close with X, change speed with S (0.25x up to 10x).
• Watching a table shows who is sitting there, what each of them just bet, their stack, how they have run tonight and across every visit they have ever made. N/P step to the next table — the ones you leave keep playing.
• V — spectate. The floor picks what you look at, holds on it for a spell, and moves to whatever is most worth watching, telling you why.
• E — the feed. Everything worth reading, with B to narrow it to the big ones.
• T — the night. How it has been going over the last minute, ten minutes, hour, or all of it, with a bar per half-minute and a table of which games are carrying the room.
• C — the customers. Biggest spenders, who is up on the house, and the regulars. Rarely the same people.
• M — the books. Handle, payouts, the realised hold, the cage, what the building costs to run, the bottom line, and every movement of money or chips by kind.
• R — tournaments. One starts up every so often: a field playing itself down to a winner.
• The money and chips in the top-right are the casino's own, live. They stay on screen everywhere in the app, including in the middle of a hand you are playing yourself.

The operations centre

[D] from the main menu opens the casino from the other side of the desk — one screen showing the whole building at once, in four sections:

┌──────────────────────────────────┬──────────────────────────────────┐
│ 1. LIVE GAMES                    │ 2. FINANCIALS                    │
│   every table, round, seats,     │   money, chips, GGR, hold,       │
│   pot, utilization, house take   │   costs, the bottom line,        │
│   and which ones have gone quiet │   buy-ins, cash-outs, cage flow  │
├──────────────────────────────────┼──────────────────────────────────┤
│ 3. EVENTS & TOURNAMENTS          │ 4. RECEPTION / CAGE              │
│   what is on, who is leading,    │   who is in the building, what   │
│   prize pools — and the feed     │   they are holding, and every    │
│   of what just happened          │   movement across the counter    │
└──────────────────────────────────┴──────────────────────────────────┘

J/K move within a section, H/L or Tab move between them, Enter opens whatever is selected, Q goes back. The layout follows your window: four panels side by side on a wide terminal, four stacked on a tall narrow one, and one at a time behind a [1][2][3][4] tab strip when there is no room for more. Nothing is ever drawn wider than the window it is in.

Opening something never builds a second version of it. Selecting a table opens the table that has been running all along; the books drill down into the ledger screen that already existed; a tournament opens its own overview, its whole field, and — once it is over — its final standings and what it came to. The floor carries on the entire time, and closing the dashboard is as invisible to the simulation as opening it.

• The cage is new, and it is where the casino stops being an abstraction. Somebody walks in, hands over cash, gets chips at 10 to the dollar, plays, and brings whatever is left back to the counter at 12 to the dollar. All of that was already happening; now there is a day book of it — who came in, what they bought, who cashed out and for how much, and the biggest movement either way tonight. Select anybody in the building to see their visit: what they brought, what they are holding, what it is worth back at the counter, and what they are up or down across every visit they have ever made.
• T — start a tournament. Pick the game, the size of the field, the entry and the starting stack; the runners are drawn from the people the casino already knows, and only if the building genuinely cannot field enough are more minted into the roster proper — they keep their names and their records afterwards. Nobody is topped up to afford a ticket they cannot afford. It then plays itself down on the simulation thread whether or not you stay to watch, and you can leave, come back and find it three rounds further on.
• G — casino settings. Speed, starting a tournament, and reseeding.

Reseeding

Reseed is not reset, and the two are deliberately different things. Reseeding replaces the stream of numbers the floor rolls from here on — and touches nothing else. The books, the people the casino knows, the tables on the floor, the rounds already played, the analytics and every finished tournament all stay exactly as they were. The simulation is not even stopped for it: the swap happens between two ticks.

The seed belongs to a running floor rather than to the saved casino, so it is not written to the save file. Open the doors again tomorrow and a fresh one is drawn, exactly as it always was.

Patrons are people the building knows. Each has an archetype — conservative, gambler, strategist, chaser, whale, beginner, hunch player — which sets the bands four traits are rolled within: nerve, appetite, discipline and read. Those decide how much they stake, how far up a table's bet ladder they reach, which table they choose, and when they walk away.

They also persist. Somebody who gets up is not deleted; they go home, and later they come back, to a floor that remembers every visit they have made. The population is bounded, so past a point a new arrival is a familiar face rather than a stranger — which is why the regulars list exists and why a name on it means something.

What no archetype and no trait does is bend an outcome. Every background round is settled by the same audited maths as the table you would play by hand, so a patron's luck is measured rather than rolled, and the "lucky player" archetype is a staking behaviour rather than a thumb on the scale. The same goes for what the room is in the mood for and for the things that happen to it over a night — a coach party, a quiet spell, a game everybody suddenly wants a seat at, a short-staffed shift. Every one of them moves a rate or a cost. Not one of them touches a payout.

Money and chips are separate quantities, and the books say so: the handle and the gaming win are counted in chips, the bottom line in cash. Chips move bet by bet at the tables; money moves only at the cage, where the house sells chips at 10 to the dollar and buys them back at 12 — so it takes a cut on every visit before anyone places a bet. Tables have limits, the top tier gets a higher one and a room of its own, the building charges its own running costs, and it all carries on from where it was the next time you open the doors.

Idle screens

Every wagering table can be left running itself: fictional punters place their own bets, the full animation plays, and results scroll by. Pick one table from the Idle Screens menu, or choose the whole floor and the casino cycles all seventeen in turn, a slot each, with a title card between them. Q returns you to the floor from anywhere in it.

Nothing an idle screen does touches your wallet or the house ledger — every chip on those screens is fictional twice over.

Economy

Chips are the table currency, dollars are the in-game cash — all of it fictional, with no real money involved anywhere. One shared wallet spans every wagering game and persists between sessions. Go broke and the house stakes you again, so no table is ever a dead end.

The house

The casino keeps a wallet too. Every time a wagering game settles, the house's balance moves by exactly the opposite of whatever the player's wallet just did, so the two ledgers are always mirror images of each other. Store currency exchanges, item purchases and anything an idle screen does don't touch it: those move chips around, but they aren't a game's outcome. The Casino screen ([C] on the main menu) shows the running balance, lifetime collected/paid totals and a per-table breakdown; the same per-table numbers appear as a house_pl line under each game on the Stats screen.

Architecture

The UI is a separate layer (src/ui/) from every game's rules — a new game only ever needs a Ctx (RNG + save file + Screen) and the widgets in src/ui/. That's what let fourteen new tables land as fourteen new files that touch nothing in the games that came before them.

• src/ui/input.rs — raw single-keypress terminal input (direct termios FFI on Unix; a line-buffered fallback elsewhere), plus the non-blocking polls that let an animation notice a keypress without stalling on one.

• src/ui/mod.rs — the Screen (alternate-screen session, buffered clear-and-redraw frames) and Scale, the shared sizing used by both renderers.

• src/ui/theme.rs — the casino color palette.

• src/ui/dice_art.rs / card_art.rs — pip-face and playing-card rendering at three sizes, and the roll animation.

• src/ui/menu.rs / widgets.rs — the boxed keyed menu, the numeric stepper, text input, progress bars, banners.

• src/games/*.rs — pure game logic, one file per game, each drawing only through the Ctx/Screen it's handed.

• src/games/cards.rs — the shared deck, shoe and both hand rankings, so six card tables share one shuffle.

• src/games/table.rs — the four beats every wagering table has in common: restaking a broke player, taking a stake, settling against both wallets, and the play-again prompt. Also the idle-budget clock the floor cycler uses to time-slice tables that don't know they're being cycled.

• src/games/floor.rs — which tables exist, and the screensaver that walks them.

• src/casino/ — the background simulation, in sixteen pieces: config.rs (every tunable, so no threshold is written down where it is used), clock.rs (simulated time, so 0.25x means fewer rounds rather than the same rounds drawn slower), event.rs (the bus; publishers push, screens pull, and the per-round traffic is counted but never kept), bank.rs (the one set of books, with a typed movement for every way money or chips can move), patron.rs and roster.rs (the people, and the fact that they outlive the tables they sit at), instance.rs (one running table), demand.rs (what the room is in the mood for, and how full it has been), happening.rs (what is going on tonight), interest.rs (how worth watching a table is), analytics.rs (the night in bounded time buckets, never recomputed), tournament.rs, reception.rs (the front desk and the cage, fed from the event bus and owning no money of its own), dashboard.rs (the operations centre's read models — views over everything above, and a source of truth for nothing), save.rs (versioned, migrated, written atomically), manager.rs (the simulation thread), and ui.rs with ui/dashboard.rs and ui/tourney_ops.rs (screens that draw snapshots and never run anything).

  The rule that keeps that honest: the UI is a viewer, not a driver. Nothing under casino/ui may advance a simulation, and nothing above manager may hold game state. The dashboard is the sharpest test of it — it shows the whole building and owns not one figure on the screen. Every number is a copy of one the bank, the roster, the feed, the analytics or the tournament system already had, taken in a single pass under the simulation's own lock and drawn only after the lock is released, so reading the casino can never stall it.

• src/economy.rs — Wallet (the player's chips, dollars and inventory) and House, the casino's mirror-image ledger, recorded explicitly at each game's settlement point rather than hooked generically into Wallet (which also handles Store exchanges that shouldn't count as winnings).

• src/history.rs — a plain-text, append-only log of Ultra Casino Dice sessions, kept separate from stats::Store's key=value settings file since it only ever grows.

Features

• ASCII pip faces and block-art card suits at three sizes, auto-fitted to the terminal, with colored output (toggleable in Options)
• Three AI difficulties — Easy is erratic, Normal holds at 20, Hard uses the near-optimal "hold at 25 minus banked" rule and pushes when behind
• Persistent stats, high scores and settings in $XDG_DATA_HOME/dice_arena/save.conf, plus a plain-text Ultra Casino Dice history log alongside it
• A live house ledger (Casino screen) tracking the casino's own profit and loss, mirror-image to the player's wallet, across every wagering table
• A four-section operations dashboard ([D]) over the running casino — tables, books, events and the cage — that adapts to the terminal and cannot disturb the thing it is watching
• Idle/attract mode for every wagering table, plus a floor-wide screensaver
• Reproducible sessions: DICE_SEED=42 cargo run
• Persistent inventory: consumables (reroll, insurance, charm) and permanent upgrades (VIP payouts, gold dice)
• Handles EOF and Ctrl+C cleanly, so the whole app is scriptable

Tests

cargo test

416 tests, covering dice-notation parsing, roll uniformity, seeded reproducibility, every Yahtzee scoring category, Luck Bet hit/sweep resolution, Roulette's payout table, Blackjack's hand totals, Ultra Casino Dice's pot math, the house ledger's zero-sum invariant, and the render geometry (every face and card is a perfect rectangle at every size, and the big ones really are 3× the small ones).

The simulation has its own share of those: that chips are only ever moved and never made, that a patron's record survives them getting up, that scoring how watchable a table is cannot touch the table, that a save which fails to write leaves the previous one exactly where it was, and — in casino/walk.rs — one long test that opens a casino, runs a night through it, and checks all twenty-four things end to end, from the doors opening to reopening it from disk afterwards.

The operations centre is tested for what it must not do as much as for what it shows: that hammering the dashboard leaves the floor plan, the seed, the books and the rounds untouched; that opening a table from it inspects the one already running rather than making another; that reseeding changes the seed and nothing else; that a tournament nobody can afford is refused and every chip taken is handed back; and that no panel ever draws wider than the box it was given, at eight terminal widths and five heights.

The house auditor

Every table's payout maths is pinned against the odds it claims, not just against itself. src/games/audit.rs plays every table hundreds of thousands of times with no rendering, through the same settlement code the table uses, and holds each to a declared band:

cargo test --release audit -- --nocapture

The rule about what belongs there is simulate only what cannot be computed. A table with a small outcome space or a closed-form distribution is priced exactly in its own file, which is strictly better:

• Slots — all 9,261 lines added up exactly.
• Chuck-a-Luck — all 216 rolls, every bet on the board.
• Roulette — all 37 pockets; every bet must carry the identical 36/37.
• Big Six — all 54 segments.
• Keno — the exact hypergeometric odds for every board size.
• Plinko — the real binomial odds of each slot.
• Scratch Cards — the print run, which sums to exactly 98%.
• Horse Racing — every runner returns the same share, by construction.

The rest — blackjack, baccarat, war, three card poker, hi-lo, video poker, bingo, mines, crash — genuinely need playing out, and that is what the harness does. Where a return depends on how the table is played, the strategy is fixed in the harness and named alongside the band, because a return with no strategy attached means nothing.