VoltThe short version. Studio won't let you submit until the math passes six critical tests: every mode's RTP between 96.0% and 96.7%, a cheapest mode costing exactly 1×, a standard deviation of at least 0.6 on 1× modes, no mode paying more than 1,000,000× or costing more than 50,000×, and at least one bet level that fits. Risk checks beyond that don't block you but lower your maximum bet. Reviewers then check the front end, the rules screen, RGS behaviour, bet replay and, for stake.us, the wording.
The critical math tests (these block submission)
| Test | Requirement |
|---|---|
| Base mode | The cheapest mode costs 1.0× the base bet |
| Base volatility | Standard deviation of every 1.0× mode is at least 0.6 |
| RTP band | Every mode's RTP is between 96.0% and 96.7% |
| Max payout | No mode pays more than 1,000,000× |
| Max cost | No mode costs more than 50,000× |
| Viable bet level | At least one bet-level template fits the 3-Star limits |
"Every mode" includes bonus buys: each has to land inside the band on its own.
File limits
- At most 20 modes per game (contact Support for exceptions).
- No single books file over 4.2 GB.
- No more than 10,000,000 events in a mode.
What the numbers should look like
Beyond the hard tests, Engine's math guidance expects:
- For slots, 100,000 to 1,000,000 simulations per mode.
- A max win that matches the rules and is "realistically obtainable", typically more frequent than 1 in 10,000,000.
- A reasonable share of paying rounds: Engine's example is that 90,000 non-paying results out of 100,000 "may be grounds for rejection".
- Non-zero wins no rarer than 1 in 50 bets.
- No gaps in the win ranges.
Risk tiers: what sets your bet limits
A second set of checks measures how much risk an operator takes on: tail probabilities of huge wins, standard deviation, and expected losses in the worst cases (CVaR and ETL). Failing them doesn't block submission; it lowers the game's maximum exposure and bet size. There are two tiers:
| Check | 2-Star | 3-Star |
|---|---|---|
| Max exposure / max bet cost | $15M / $100k | $50M / $500k |
| Max payout / cost multiplier | 50,000× / 1,000× | 100,000× / 5,000× |
| Max standard deviation | 50.0 | 60.0 |
| CVaR per stake / absolute | 700 / 20,000 | 700 / 50,000 |
| P(win ≥ 5,000×) / P(win ≥ 10,000×) | 0.010 / 0.005 | 0.050 / 0.010 |
Failures are grouped into six classes, and each failed class cuts the caps further (at 3-Star, one failed class gives $25M / $500k; all six give $500k / $10k). Engine's page lists more rows than this summary. So a 1,000,000× max win passes the critical test but sits far outside the 3-Star risk limit of 100,000×; decide which you want before you design the feature.
The rules screen
The game has to explain itself: the rules, the RTP of the game and of each mode, the max win per mode, every symbol's payouts, special symbols' values, how features trigger and retrigger, each mode's cost, and Engine's general disclaimer (reviewers check every point of it).
Controls and display
- Bet size can be changed, through every bet level the RGS allows. Balance is shown, and the win counter counts up.
- A sound-off option. The space bar places a bet.
- Autoplay asks for confirmation, and so does any mode costing more than 2× the base bet.
- Fast play stays legible.
- Works on mobile and in the mini-player (Popout S and L); no scrolling; double-tap zoom disabled.
- Unique art and audio: no web-SDK sample assets, no Stake Engine logo or loader, no visual bugs. Everything loads from the build: no external fonts or images.
RGS behaviour
- Never hard-code bet levels, the default bet or the RGS address; reviewers launch with an invalid
rgs_urland expect an error. - Restore the bet amount of an active round when the game reloads.
- Don't call
/playwithout enough balance, and only call/end-roundfor winning rounds. - Show sub-cent payouts precisely.
- English is the only required language, with English as the fallback. Reviewers test USD, EUR, CAD, MXN and JPY, plus XSC and XGC in social mode.
Bet replay
Mandatory for every game. Replay loads a past round from its game, version, mode and event ID without a session, shows Play and then Play Again, hides the bet controls, shows the real cost, and works in the small popout. Be ready to give reviewers round IDs per mode for a normal win, a big win, the win cap, a loss and a bonus trigger.
stake.us (social and sweepstakes)
Games are considered for stake.us automatically if they pass the language rules in social mode (social=true). Engine publishes a table of 30+ restricted words with replacements, for example bet → play, buy bonus → get bonus, pay → win, cash or money → coins, withdraw → redeem. Mode names can't contain "buy", "bet" or "pay" and must match across the game, replay and math files. SC and GC amounts take no "$" prefix, and social mode is English only. Studio has a Social Mode toggle for testing.
What's not allowed
- State that carries between rounds: jackpots, gamble features, continuation or early cash-out.
- Games that aren't original, including pre-purchased or licensed games.
- Stake branding, or anyone else's intellectual property.
- Anything that appeals to minors, including child-like characters.
Before you submit
Studio also requires a 3:4 tile set as the cover and a 16:9 cover image in the media library (tiles are built in Studio's Media Editor and exported at 408×546 and 640×360), a published front version and math version, and that you're within the open-review limit: one at a time until your first game is live, five after that.
The math SDK's own verification script is a useful first pass, but a few of its thresholds differ from Engine's current docs (its tail-probability limits match 2-Star rather than 3-Star, its CVaR limit is 800 rather than 700, and it requires payouts in 0.1× steps, which the docs don't state). It also warns when modes' RTPs differ by more than 0.05; the docs set no such rule beyond the 96.0–96.7% band. Third-party pages still quoting a 90–98% RTP range or a 1-in-20 hit rate are out of date.
Frequently asked questions
What RTP does Stake Engine require?
Every mode, including bonus buys, must have an RTP between 96.0% and 96.7%.
What is the maximum win allowed on Stake Engine?
The critical limit is 1,000,000× per mode. The 3-Star risk tier allows up to 100,000×; above that the game still passes but gets lower bet limits.
Can I add a bonus buy to a Stake Engine game?
Yes, as its own mode, with its own RTP inside the 96.0–96.7% band, a cost of at most 50,000×, and a confirmation before purchase (any mode over 2× the base bet needs one).
Are jackpots or gamble features allowed on Stake Engine?
No. Games must be stateless, so jackpots, gamble features, continuation and early cash-out aren't allowed.
What words are banned for stake.us games?
Engine lists 30+ terms for social mode with replacements, such as bet → play, buy bonus → get bonus, pay → win, cash → coins and withdraw → redeem. Mode names can't contain buy, bet or pay.
What minimum hit rate does Stake Engine expect?
Non-zero wins should come no less often than 1 in 50 bets. It's guidance rather than one of the critical tests.
Sources: Engine docs (approval guidelines, math verification, submission checklist, front-end and RGS communication, game replay, jurisdiction requirements, game tile requirements) and the Stake Engine math SDK's verification script. Checked October 22, 2026.