Plain English
Gambling sites lean on a lot of jargon, and most of it is simpler than it sounds. These are the terms that come up on this site and in the games themselves, explained without the maths.
The share of everything you bet that the casino expects to keep.
If a game has a 1% house edge, you lose 1% of everything you stake over the long run — not 1% of your deposit. That distinction matters enormously. Put £100 through a game twenty times and you have staked £2,000, so a 1% edge expects to cost you £20, not £1.
Full guide to house edge →The same number as house edge, counted from the other end.
RTP and house edge always add up to 100%. A game with a 4% house edge has 96% RTP. A game with no house edge at all has 100% RTP. Slot machines usually sit around 96%; Duel’s Originals mostly sit at 100%.
How RTP and house edge relate →When a payout exactly matches the chance of winning.
If something happens one time in four, true odds pay 4×. Most casino games pay slightly less than that, and the gap is where their profit comes from. A game paying true odds has no built-in advantage over you — you break even in the long run rather than slowly losing.
How wildly your balance swings, regardless of the odds.
A game can be perfectly fair and still take your whole balance in twenty minutes. Variance is that swing. High-variance games (a 1,000× Limbo target) lose for long stretches then pay big; low-variance games (Dice at a 90% win chance) grind along with small moves. Fairness changes where you end up eventually; variance decides whether you are still there to see it.
A way to prove a result was decided before you bet on it.
Before you play, the casino shows you a scrambled fingerprint (a "hash") of a secret number. You add a number of your own. Together they produce every result. Afterwards the casino reveals its secret number, and you can check it matches the fingerprint you were shown. If it does, the result could not have been changed after you bet.
How to verify a bet yourself →The casino’s half of the randomness.
A long secret string the casino generates and commits to before you bet by showing you its hash. Once you rotate your seed it is revealed, so you can check every round it produced.
Your half of the randomness.
A string you choose yourself. Because the result depends on it and the casino committed to its own seed before knowing yours, it cannot pick a seed that produces the outcomes it wants. You can change it whenever you like.
A counter that ticks up with each bet.
Your seeds stay the same across a session, so something has to make each bet different. The nonce is simply a number that increases by one every round — bet one is nonce 1, bet two is nonce 2, and so on.
The total amount you have bet, not the amount you deposited.
This is the number a house edge applies to, and it is almost always far larger than your deposit, because you keep re-betting money you win. It is also the number bonus wagering requirements are measured against.
How much you must bet before a bonus can be withdrawn.
Usually written as a multiple, like "30×". A £50 bonus at 30× means staking £1,500 before the money is yours. This single number decides whether a bonus is generous or worthless, and it matters far more than the headline amount.
How much a given game counts toward a wagering requirement.
Casinos often count slots at 100% but low-edge games at 10% or not at all, because fair games cost them more to clear. Always check the weighting table before assuming you can clear a bonus on the games you actually want to play.
A percentage of what you bet, credited back to you.
On a normal casino game rakeback is a partial refund on a loss you were always expected to take. On a game with no house edge there is no expected loss to refund, so anything credited on top is genuinely extra — which is why the combination is worth looking for.
The mathematically correct decision for every blackjack hand.
Blackjack is solved: for any hand against any dealer upcard, exactly one action is best. The full chart is free to look up and takes an hour to learn. Playing without it costs roughly 1–2% of everything you stake, which on a fair table is the entire difference between breaking even and losing.
What a bet is worth on average, over a great many repetitions.
A £10 bet with an expected value of £10 is break-even: you neither gain nor lose in the long run. One with an expected value of £9.60 loses 4% of everything you stake. Expected value says nothing about any single session — that is variance.
The reason a fair game can still take everything.
If you keep betting against an opponent with far more money than you, and you never stop, you will eventually hit zero — even at perfectly fair odds. It is a mathematical result, not a warning. The only thing that prevents it is deciding in advance when to stop.
The two that matter most. House edge tells you what a game costs you over time. Variance tells you how rough the ride is getting there. A game can be perfectly fair and still be dangerous — those are separate things, and most people only ever hear about the first.
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Every Duel Original has its own guide covering the payouts, how to play it and what to watch for.
18+. Wagering requirements apply. Terms set by the operator and subject to change.