Public Audit + RTP Checker for Groomer's Van

We just put a public audit and RTP checker for Groomer's Van live at rawcrew.live/groomers-van. It runs entirely in your browser, costs nothing, and lets anyone replay a spin from its seeds or simulate the whole base game across any nonce range.

If you have ever stared at a "provably fair" badge and wondered who actually checks the math, this is the answer. We built it so you do not have to take Duel's word for it. You do not have to take ours either.

First, What Is Groomer's Van

Groomer's Van is Duel Casino's flagship slot and, as far as we are aware, the first slot ever shipped to players with a published 100% RTP. The advertised base game return is 99.9996511593%, which is effectively 100% once you round. Most slots in the wild sit between 94% and 97%. A few "high RTP" slots brag about 98%. Groomer's Van is in a category by itself.

The format is a 6-reel, 11-symbol grid built around a kangaroo mascot in a top hat. Hit rate is around 45.75%, the bonus round triggers roughly once every 227 spins, and the max win is 5,000x your bet at a frequency of about 1 in 614 million spins. It is high variance by design. The 100% RTP does not mean every session breaks even. It means that across millions of spins, the house edge converges to zero.

That is a real shift in how a casino game can be priced. It is also the reason an open audit matters. Numbers that good only mean something if anyone can check them.

Why an Audit Tool, Not Another Review

"Provably fair" only means something if someone proves it. Most casinos that ship a verifier hide it three menus deep, use a UI nobody understands, and make you trust that the seeds and config they show you are the same ones the game actually used. The math is auditable in theory and ignored in practice.

We wanted something different. A page anyone can land on, with the seeds, the algorithm, and the results all in one place. Run it once and you have receipts. Run it ten thousand times and you have a sample.

The two pieces that make up the audit tool, both running client-side.

What the Tool Actually Does

There are two parts.

The Validator takes a server seed, a client seed, and a nonce range. It re-derives the HMAC-SHA256 outcome locally, exactly the way Duel's algorithm does it, and compares the result to what was paid out. It also verifies the SHA-256 hash of the game configuration. If the reel weights or paytable on Duel's side ever changed, the hash would no longer match and the validator would flag it.

That second piece matters more than people realise. A fair RNG on top of a swapped reel config is not a fair game. Hashing the config makes the integrity of the whole package checkable, not just the dice roll.

The Seeded RTP Replay is the heavier tool. Pick a server seed, a client seed, and how many spins to simulate. The browser runs them, draws a cumulative RTP curve and a balance chart, and gives you a paginated table of every nonce, every win multiplier, and every bonus trigger. Want to see what variance actually looks like across 50,000 spins? It is right there, no spreadsheet required.

Try It Yourself

Run the Groomer's Van audit in your browser

Replay any spin from its seeds, verify the config hash, and simulate RTP across any nonce range. Free, no login, runs entirely client-side.

Open the Audit Tool →

The Math Duel's Devs Confirmed

Alongside the tool, Duel's game devs sent us their own per-spin distribution for Groomer's Van. We published the full set in the "Official math" section on the page. The headline numbers:

• Base game RTP: 99.9996511593% (essentially 100%, as advertised)
• Hit rate: 45.75% of spins return at least the bet
• Bonus trigger: roughly 1 in 227 spins land 3+ scatters
• Standard deviation: 12.86 (high variance, as expected for a slot with a 5,000x ceiling)
• Max win: 5,000x your bet, with a frequency of about 1 in 614,000,000 spins

That last number is worth sitting with for a second. A 5,000x hit is not a "long shot". It is a once-in-a-career event for almost every player who ever opens this game. The slot's ceiling exists, but the road there is paved with a lot of base-game spins that look nothing like the highlight reels.

Per-spin payout rarities published by Duel's devs. The drop-off past 1,000x is steep.

What We Cross-Checked

The point of an audit is not to repeat someone's claim. It is to test it.

The piece we could verify directly was the reel-weight matrix. Duel's devs sent us the full table: 6 reels, 11 symbols per reel, integer weights for each cell. We compared that table against the configuration our verifier has been using in the public tool, which we pulled from the game's published verification panel. The two matched byte-for-byte. Same numbers, same ordering, no rounding, no drift.

The reel-weight matrix is the foundation of every spin. If this drifts, RTP drifts with it.

That is the boring-but-critical part. Our HMAC-SHA256 pipeline is not running on a guess of the configuration. It is running on the same configuration the live game uses. So when our simulator returns an RTP near 100% over a few hundred thousand seeded spins, that result is not a coincidence. It is the same maths converging on the same expected value.

For the rest of the dev numbers (the standard deviation, the variance, the deep payout-bucket frequencies past 5,000x), we republished what they sent us as-given. We did not independently re-derive the full distribution. The badge on the page reads "Dev-provided" for that reason. We are not going to dress up someone else's number as ours.

Why 100% RTP Is Not a Free Lunch

It would be easy to read "RTP near 100%" and assume the game is breakeven. It is not, and the math is not the reason.

The standard deviation here is 12.86. That is enormous. With a 5,000x ceiling and a hit rate under 50%, the slot is built to swing hard in both directions. Theoretical RTP is what you get if you are the entire universe of players combined, spinning forever. It is not what one person sees on a Friday night session.

Run the RTP Replay yourself. Watch the cumulative-RTP curve at 100 spins. Then 1,000. Then 50,000. The line wanders before it settles. That wander is where bankrolls go.

What This Tool Cannot Tell You

Worth being clear about the limits.

The validator confirms that a given spin came out the way the algorithm and the config say it should. It cannot tell you whether the seeds you were shown are the seeds the server actually used at the moment of your spin. That trust still rests on the seed-commit step Duel publishes before each session begins. If a casino swapped seeds mid-session, no client-side verifier in the world would catch it.

The RTP Replay tells you the long-run expectation of the published configuration. It cannot tell you that the operator is not running a different config behind the scenes for a specific player segment. We have written before about how operators can change RTP versions on the same slot without telling anyone, and that risk is structural, not specific to Duel.

What it can do is shrink the surface area where things can go wrong without anyone noticing. Hashes can be checked. Algorithms can be replayed. Distributions can be sampled. Every box this tool ticks is one less place for a quiet change to live.

What We Think

For the first time we are aware of, a public, browser-based audit page exists for a real money slot, sitting outside the casino itself. The math the operator published, the math their devs confirmed, and the math anyone can reproduce on their own machine all line up. That is a healthier baseline than "trust us".

It also raises a question worth asking other operators. If a six-reel slot with a 5,000x ceiling can be opened up like this, what is the excuse for the rest of the industry? Why do we still have games where the player has no realistic way to check that the spin they just lost was the spin the algorithm would have produced?

The tool is at rawcrew.live/groomers-van. If you find something off in the audit, tell us. We would rather hear it than not.