Most online slots and many table games use a random number generator (RNG) — software that outputs values mapped to game results. Under the UK Gambling Commission’s licensing regime, remote operators must ensure games are fair and that relevant systems are tested appropriately. That duty sits alongside advertising rules and player-protection tools.
UK Reel Trails does not certify games. We explain the vocabulary so readers can interpret footer seals and supplier claims with a cooler head.
What an RNG actually does
An RNG continuously generates numbers. When you press spin or deal, the game uses the current value (or a derived value) to decide the outcome according to its rules and paytable. Properly implemented, prior results do not “owe” a win, and patterns you think you see in short samples are usually noise.
Return to player (RTP)
RTP is a long-run statistical average built into the game mathematics — for example, a theoretical percentage returned to players across a very large number of rounds. It is not a forecast for your next session. Volatility (how unevenly wins are distributed) is a separate design choice.
Live dealer games
Live roulette, blackjack and similar titles use physical equipment streamed from a studio, with procedures and oversight rather than a classic slot RNG for the wheel or cards. Digital side bets or graphics overlays may still rely on certified random components. The fairness question becomes: are the studio processes and any RNG elements properly controlled and tested?
Independent testing labs
Specialist laboratories assess gaming software and RNGs against technical standards. Well-known names in the industry include eCOGRA, GLI (Gaming Laboratories International), BMM Testlabs and iTech Labs, among others. Operators and suppliers may publish certificates or seals referencing such labs.
A seal typically indicates that a specific product build or RNG was evaluated at a point in time against defined criteria. It is not a perpetual guarantee that every future update is covered without retesting, nor proof that a marketing claim about “luck” is true.
What seals do — and do not — mean
- Do: show engagement with formal testing processes recognised in regulated markets.
- Do: sit alongside UKGC licensing duties for operators serving Great Britain.
- Do not: promise personal winnings, “hot” machines or beatable sequences.
- Do not: replace reading game rules, stake limits and your own safer-play settings.
Treat a lab mark as documentation of process, not as a tip sheet.
Practical checklist for players
Before you play a new title on a licensed site, confirm you are on the operator’s real domain, note the UKGC licence references in the footer, and open the game’s help file for rules and RTP information where published. Set deposit or loss limits first. If gambling stops feeling like controlled entertainment, use time-outs or GAMSTOP.
UKGC
GAMSTOP
GamCare
GambleAware