99% RTP Slots: The Games That Return Almost Everything
Only two slots in the entire UK market publish above 99% RTP. The rest of the elite tier sits between 97% and 98.6%.
Only two slots in the entire UK market publish above 99% RTP. Book of 99 by Relax Gaming at 99.00% and Goblin's Cave by Playtech at 99.32%. At these RTPs, the house edge is 1% or less — comparable to blackjack with basic strategy and dramatically better than any other slot.
Book of 99 uses the standard "Book of" expanding-symbol free spins mechanic. The 99.00% RTP is not a typo. A player wagering £1,000 expects to lose £10. The same £1,000 on a typical 94% game costs £60. The catch: availability is limited. Many UK casinos either do not carry Book of 99 or restrict it from bonus play. Relax Gaming offers 2-3 deployment tiers, so verify the deployed figure at your casino.
Goblin's Cave is a Playtech legacy title from the early 2000s. The 99.32% is the highest published RTP of any slot anywhere. The game uses a player-decision hold mechanic similar to video poker — optimal hold strategy contributes to the return exceeding 99%. Availability in 2026 is extremely limited. Most UK casinos have removed it from their lobbies.
Below 99%, the next-best options are: Blood Suckers at 98.00% fixed (NetEnt — guaranteed at every casino), 1429 Uncharted Seas at 98.50% fixed (Thunderkick), White Rabbit at 97.72% fixed (Big Time Gaming legacy single-build), and Steam Tower at 97.04% fixed (NetEnt pre-variable era). These form the elite tier of UK slot RTP.
The two 99%+ RTP slots
These are the only published slots above 99% RTP available — sometimes — in the UK market.
The next tier: 97%–98.6% RTP
Widely available titles with elite RTP. Most are fixed-RTP single-builds — guaranteed at every UKGC-licensed casino.
FAQ
Are there really 99% RTP slots?
Yes. Book of 99 at 99.00% and Goblin's Cave at 99.32%. Both are real but rarely available at UK casinos.
Why don't casinos offer 99% RTP slots?
A 99% game generates almost no revenue for the casino. Operators remove or restrict them to protect margins.
What is the highest RTP slot I can actually play?
Blood Suckers at 98.00% fixed is the highest widely available slot. Book of 99 and Goblin's Cave are higher but hard to find.