The math.

Every number here is a SPEC §2 constant or derived from one. The table is the same bytes in the program, in the math package and on this page.

Return to player, written out

Return to player is the sum of every multiplier times its probability. Probabilities are stored in parts per million and sum to exactly 1,000,000: 50 + 110 + 160 + 200 + 450 + 1,200 + 3,000 + 6,000 + 14,000 + 16,000 + 30,000 + 35,000 + 116,230 + 70,000 + 80,000 + 40,000 + 120,000 + 467,600 = 1,000,000.

Multiplier times probability, row by row: 100×50 + 69×110 + 50×160 + 42×200 + 25×450 + 15×1,200 + 10×3,000 + 7×6,000 + 5×14,000 + 4.2×16,000 + 3×30,000 + 2.5×35,000 + 2×116,230 + 1.5×70,000 + 1×80,000 + 0.69×40,000 + 0.5×120,000 + 0×467,600
= 5,000 + 7,590 + 8,000 + 8,400 + 11,250 + 18,000 + 30,000 + 42,000 + 70,000 + 67,200 + 90,000 + 87,500 + 232,460 + 105,000 + 80,000 + 27,600 + 60,000 + 0
= 950,000 ppm.

950,000 ÷ 1,000,000 = 0.95000. Return to player is 95.000%, exactly, not rounded. The house edge, THE VIG, is the other 5.000%. For comparison: Nevada slot machines returned 92.85% statewide in 2025; US sportsbooks held 10.16% of handle in 2025, which is a return of about 89.8%.

Per pull: 62.76% lose money (0x, 0.5x, 0.69x), 8.00% return exactly the stake (1x), 29.24% profit (1.5x and above). Standard deviation of the multiplier is 1.97. The 100x row is 50 ppm: 1 in 20,000. Over 10,000 pulls the chance of seeing at least one is 39.3%.

The table is the same bytes in the program, in the math package and on this page. Its sha256 is fbce9c2e0bf90bd1a857984bfa83c930d4a768eb1e88a805f9fbdb215d69e1d9. If the three ever disagree, the program is wrong and the tests fail before it ships.

THE LADDER

How a pull is decided

The randomness is 32 bytes from the VRF. The first 8 bytes are read as a little-endian integer and reduced modulo 1,000,000 to a roll between 0 and 999,999. (The sliver of the 64-bit range that would bias the modulo is rejected and the next 8 bytes are tried; the residual bias is below 5.4 × 10⁻¹⁴ and documented.) The roll is compared to the ladder in rare-first order: under 50 is THE CARTOON; under 160 is NICE NICE; under 320 is GENERATIONAL; under 520 is THE ANSWER; under 970 is RETIRED; under 2,170 is QUIT YOUR JOB; under 5,170 is LAMBO; under 11,170 is LUCKY; under 25,170 is GRADUATED; under 41,170 is BLAZED; under 71,170 is SCREENSHOT; under 106,170 is HALF A SCREENSHOT; under 222,400 is WE'RE SO BACK; under 292,400 is GAS COVERED; under 372,400 is NOTHING HAPPENED; under 412,400 is NICE; under 532,400 is DUST; everything else is RUGGED. Payout is the stake times the multiplier, floored to the token's smallest unit. The dust from flooring stays in the pool.

THE CEILING

Max bet = free pool × 0.1%. The free pool is THE HOUSE minus every payout that is currently reserved for a pending pull. Every pull reserves 100× its stake the moment it is placed, so the pool can always pay the top row no matter what lands. A 100x hit therefore cannot take more than 10% of the free pool in one pull. The ceiling moves with the pool: it rises when the pool grows and shrinks when the pool shrinks. The admin can tune the percentage between 0.01% and 0.2% and nothing else about it. No one can raise it by hand, and no one can lower the reserve.

Minimum bet is 1,000 $GAMBLE. If the pool is so small that the ceiling drops below the minimum, the button turns off until someone seeds it.

Right now: THE HOUSE 196,056,084 · reserved 0 · free 196,056,084 · THE CEILING 196,056 $GAMBLE.

THE SEED LINE, RAPTURE, THE LAST GAMBLER

THE SEED LINE is the total ever seeded into the pool: the founder's 20% of supply on day one, plus anything anyone adds later with the permissionless seed instruction. After every settle, if the free pool is above THE SEED LINE, the excess is swept into the RAPTURE VAULT. The pool is therefore held at the seed line and the house's entire edge, over time, ends up in the vault.

The vault is paid out by THE LAST GAMBLER:

• The clock is armed once the vault holds at least 1% of THE SEED LINE. Only an armed clock can be raptured. Qualifying pulls set THE LAST GAMBLER and the deadline whether or not it is armed; the moment the vault arms, the deadline is pushed to at least 10 minutes out, so nobody can rapture a stale clock the instant it arms.
• A qualifying pull is at least 1% of THE CEILING or 2% of the vault, whichever is larger, capped at THE CEILING. So as the vault grows, keeping the clock alive costs more. A bot that wants to hold the clock on a big vault has to pay for it, and what it pays is vigged like everything else.
• Each qualifying pull extends the deadline by up to 10 minutes, scaled by the pull's size relative to the ceiling and shrunk as the vault grows past its arming level. Never less than 60 seconds; never more than 15 minutes from now. The puller becomes THE LAST GAMBLER.
• When the deadline passes, anyone may call rapture. Half of the vault, floored, goes to THE LAST GAMBLER immediately. The other half goes to THE ROUND: everyone who pulled since the previous rapture, split in proportion to what each wallet wagered that round. Every pull counts toward the round, qualifying or not.
• Round shares are claimable for 30 days. Claim from the vault panel on /receipts or with claim_round. Claiming also returns your stake-account rent. After 30 days, whatever was not claimed goes back into the RAPTURE VAULT and becomes part of the next pot.

Snipers are expected. The bots are also gamblers; their vig feeds the next pot.

Right now: RAPTURE VAULT 2,263,500 · arms at 2,000,000 · ARMED · a qualifying pull is at least 45,270 $GAMBLE · round 7.

House profit: 0, by construction

There is no withdraw instruction. The only instructions that move tokens out of the program's vaults are settle (your payout, and the sweep into the RAPTURE VAULT), refund_expired (your stake back if the oracle never answers), claim_payout (a payout that could not be delivered at settle time), rapture (half to THE LAST GAMBLER, half into THE ROUND), claim_round (your round share) and expire_round (unclaimed round shares back into the vault). The payees are the player, THE LAST GAMBLER, round stakers, or the program's own vaults. There is no fee switch. The admin can pause new pulls, tune the bounded parameters above, change the oracle queue to another queue owned by the VRF program, hand the admin key over, or renounce it forever. None of those move a token.

Read the IDL. Count the instructions. The one you're looking for isn't there.

Randomness

Every pull requests randomness from MagicBlock VRF inside the same transaction you sign. You sign once. The oracle verifies the VRF proof on-chain and then calls our settle instruction with the 32 bytes; settle checks that the caller is the VRF program's identity and refuses anyone else. We never see the randomness before you do, and we cannot call settle ourselves. The 0.0005 SOL fee on each pull is the oracle's, paid by you to the queue, not to us.

What "provably fair" means here: every input to your outcome is on-chain and anyone can recompute it. It does not mean trustless. The oracle set is permissioned by MagicBlock. If the oracle never answers, your stake is refundable after 750 slots (about five minutes) by anyone calling refund_expired; it goes back to you, not to the pool.

Verify it yourself

• Open any pull at /receipts?q={signature or bet address}. Everything on that card is read from the chain, not from our server.
• Take the randomness field. Read bytes 0–8 little-endian, mod 1,000,000. That is the roll.
• Find the first ladder row whose bound is above the roll. That is the tier. Multiply the stake. That is the payout.
• Or run it: pnpm --filter @gamble/math cli -- verify <randomness-hex> <amount>.
• Read the program: github.com/justgamble-xyz/justgamble. Read the IDL: idl/justgamble.json. The deployed program: F347v3A6ckTBZhdsfyHeNic4juipToHMMZgGt45BkNux (devnet). The deployed hash is checked against the source with solana-verify before mainnet.