Last updated: May 2026. Comparative testing across the four featured AU casinos plus standalone NetEnt-licensed venues for Mega Joker and Jackpot 6000.
"99% RTP" is the badge Book of 99 wears in every marketing asset. But it's not technically the only slot with a 99%-or-higher RTP. A small handful of niche games — mostly fruit-machine sequels designed for advantage players — claim higher returns when played with optimal strategy. None of them are quite like Book of 99, which is why Book of 99 dominates the conversation despite the existence of these technical competitors. This article compares Book of 99 head-to-head against every other notable 99%+ RTP slot, explains why they're rare, and helps you decide if you should chase one of the alternatives or stick with the modern book-slot champion.
Skip the comparison and play18+ · BetStop · gamblinghelponline.org.au
The 99%+ club — who's in it?
Truly 99%+ RTP slots in the mainstream market are rare. Here's the list:
| Slot | Studio | RTP | Year | Game type |
|---|---|---|---|---|
| Book of 99 | Relax Gaming | 99% | 2021 | Modern video slot |
| Mega Joker | NetEnt | 99% (with optimal supermeter play) | 2014 | Fruit machine, supermeter |
| Jackpot 6000 | NetEnt | 98.86% (with optimal play) | 2013 | Fruit machine, supermeter |
| Ugga Bugga | Playtech | 99.07% | 2009 | Multi-payline, tribal theme |
| 1429 Uncharted Seas | Thunderkick | 98.6% | 2015 | Modern video slot |
| Blood Suckers | NetEnt | 98% | 2009 | Modern video slot, vampire theme |
| Mega Joker (Microgaming) | Microgaming | 99% | 2012 | Different game, same name — fruit machine |
Roughly seven titles in the entire online slot industry sit at 98%+. Of these, Book of 99 is the only modern video slot with 99% RTP at default settings, no optional gameplay required — see our 99% RTP math walkthrough for why that "default" qualifier matters.
Book of 99 vs Mega Joker (NetEnt)
The headline rival. Mega Joker is the cult favourite among advantage players and high-RTP hunters.
| Spec | Book of 99 | Mega Joker (NetEnt) |
|---|---|---|
| RTP | 99% (default) | 99% (only with optimal supermeter play) |
| Default RTP without strategy | 99% | 76.9% |
| Game style | Modern video slot | Fruit machine with supermeter |
| Grid | 5 × 3 | 3 × 3 (base) + 3 × 1 (supermeter) |
| Volatility | High | Medium |
| Max win | 12,075× | ~2,000× |
| Skill component | None | Yes — requires supermeter strategy |
| Mobile UX | Excellent | Functional |
The catch with Mega Joker: the 99% RTP only applies when you play the supermeter — a separate phase that activates after wins where you must choose to either bank the win or risk it for higher-paying spins. (No such strategy needed on Book of 99 — see the beginner walkthrough.) If you ignore the supermeter and just take your wins, the effective RTP drops to 76.9% — one of the worst in the industry.
Verdict: Book of 99 wins for casual players. Mega Joker wins for committed advantage players willing to learn the supermeter math.
Book of 99 vs Jackpot 6000 (NetEnt)
Jackpot 6000 is Mega Joker's older sibling — same fruit-machine pattern.
| Spec | Book of 99 | Jackpot 6000 |
|---|---|---|
| RTP | 99% (default) | 98.86% (with optimal supermeter) |
| Default RTP | 99% | 75% |
| Game style | Modern video slot | Classic fruit machine |
| Max win | 12,075× stake | 6,000 coins (modest) |
| Theme | Greek mythology | Generic fruits + bells |
| Visual | 2021-era | 2013 retro |
Same supermeter trap as Mega Joker. Default play is bad. Optimal play gets you to the headline RTP. Most casual players don't play optimally.
Verdict: Book of 99 wins decisively. Jackpot 6000 is a niche curiosity.
Book of 99 vs Ugga Bugga (Playtech)
The dark horse of the high-RTP genre. Ugga Bugga sits at 99.07% RTP — technically the highest in the entire online slot category.
| Spec | Book of 99 | Ugga Bugga |
|---|---|---|
| RTP | 99% | 99.07% |
| Game style | Modern video slot | Multi-payline with hold feature |
| Grid | 5 × 3 | 4 × 1 (base) + 9 holds |
| Volatility | High | Low-Medium |
| Max win | 12,075× | 70× stake |
| Mechanic | Expanding symbol, free spins | Hold feature, classic |
| Theme | Greek mythology | Tribal / jungle |
| Bonus rounds | Free spins | None |
Why Ugga Bugga loses despite higher RTP:
- Max win of 70× stake means even a "huge" hit is modest.
- No bonus rounds — gameplay is repetitive.
- 2009-era visuals.
- Low excitement potential.
Ugga Bugga is the choice for wagering-bonus clearing specifically — the high RTP minimises expected loss across required play volume. But for session entertainment, it's painfully boring compared to Book of 99.
Verdict: Book of 99 wins for entertainment. Ugga Bugga wins specifically for grinding wagering at minimum expected loss.
Book of 99 vs Blood Suckers (NetEnt)
98% RTP, modern visuals, decent gameplay. Often listed alongside the 99% club.
| Spec | Book of 99 | Blood Suckers |
|---|---|---|
| RTP | 99% | 98% |
| Volatility | High | Medium |
| Max win | 12,075× | 900× stake |
| Theme | Greek mythology | Vampires |
| Bonus | Expanding symbol free spins | Pick-a-coffin bonus + free spins |
Verdict: Book of 99 wins on RTP (by 1 point), max win (by 13×), and modernity. Blood Suckers is fine but not in the same league.
Book of 99 vs 1429 Uncharted Seas (Thunderkick)
98.6% RTP, beautiful art, modest payouts.
| Spec | Book of 99 | 1429 Uncharted Seas |
|---|---|---|
| RTP | 99% | 98.6% |
| Volatility | High | Medium |
| Max win | 12,075× | 50,000 coins (~2,500× stake at default) |
| Theme | Greek mythology | Medieval cartography / sea monsters |
| Visual | Modern, polished | Beautiful, distinctive |
Verdict: Book of 99 wins on RTP and max win. 1429 Uncharted Seas is the visually more interesting game but mathematically inferior.
Why aren't there more 99% slots?
Three reasons:
1. Margin. A 4-5% house edge generates 4-5× more revenue per dollar wagered than a 1% house edge. Studios with profit-maximising mandates don't make 99% RTP games. Relax Gaming made Book of 99 as a marketing showcase, not a profit driver — and the buzz around the RTP has generated enough player adoption to justify the lower margin.
2. Casino reluctance. Casinos prefer to feature games with higher house edges in their lobbies because they generate more gross revenue. A casino running Book of 99 prominently is voluntarily reducing its own margin. Some casinos quietly de-prioritise high-RTP slots in their game-tile rankings or exclude them from wagering-contribution lists.
3. Player perception. Casual players don't compare RTP — they compare visuals, themes, and the "feel" of bonus rounds. A 96% RTP game with flashy animations sells better than a 99% RTP game with quieter visuals, despite the math. Studios have learned to compete on visual spectacle, not on math.
The wagering-bonus angle
If you're clearing welcome-offer wagering, every high-RTP slot in this comparison can help you minimise expected loss. The math:
| Game | RTP | Expected loss per A$1,000 wagered |
|---|---|---|
| Book of 99 | 99% | A$10 |
| Ugga Bugga | 99.07% | A$9.30 |
| Mega Joker (optimal) | 99% | A$10 |
| 1429 Uncharted Seas | 98.6% | A$14 |
| Blood Suckers | 98% | A$20 |
| Average 96% slot | 96% | A$40 |
| Book of Ra Deluxe | 95.1% | A$49 |
Critical caveat: many casinos exclude high-RTP slots from wagering contribution specifically to prevent this advantage-play. Always read the bonus terms. If Book of 99 contributes 0% to wagering at your casino (which happens at some), the math collapses and any 96-97% slot included in wagering becomes the better grinder.
The "feel" factor
Specs aside, how does each game actually feel to play?
- Book of 99: classic book-slot rhythm. Long dry stretches in base game, dramatic bonus triggers, the lottery-ticket moment of the expander reveal. Modern visuals. Active community.
- Mega Joker: retro fruit-machine vibe. Demanding to play optimally (you have to make supermeter decisions every win). Niche appeal.
- Ugga Bugga: repetitive. The hold feature gives some agency but the gameplay loop becomes monotonous within 50 spins. RTP-grinder only.
- Blood Suckers: competent vampire-themed slot. Pick-a-coffin bonus is novel. Less exciting than book genre bonuses.
- 1429 Uncharted Seas: beautiful but quiet. The art is the standout; the gameplay is unremarkable.
Book of 99 has the best entertainment-to-RTP ratio of the entire 98%+ class.
Which 99% slot for what scenario
| Scenario | Pick |
|---|---|
| Casual session, real money, high variance acceptable | Book of 99 |
| Max-win chasing | Book of 99 (12,075× ceiling beats every alternative) |
| Wagering bonus clear (where high-RTP is allowed) | Ugga Bugga or Book of 99 |
| Wagering bonus clear (where Book of 99 is excluded) | Best slot still permitted; check terms |
| Advantage play with active strategy | Mega Joker (supermeter) |
| Retro fruit-machine aesthetic | Jackpot 6000 or Mega Joker |
| Beautiful art, modest payouts | 1429 Uncharted Seas |
| Anything else, default choice | Book of 99 |
Verdict
For Australian players in 2026, Book of 99 is the default choice in the 99%+ RTP class for almost every use case. It combines the best math with the best max-win, the best visual production, the best mobile UX, and the broadest casino availability. The alternatives are niche — Mega Joker for committed supermeter players, Ugga Bugga for pure wagering grinding, the rest for specific tastes or specific scenarios.
If you want the highest-RTP mainstream pokie experience, you want Book of 99 — and you'll want to play it at one of our vetted AU casinos running the certified 99% build.
Play the highest-RTP mainstream pokie▶ Play Book of 99 · 🎁 Welcome Bonus
18+ · BetStop · gamblinghelponline.org.au · T&Cs apply
Quick FAQ
Is there any slot with higher than 99% RTP? Ugga Bugga at 99.07% is technically higher. Mega Joker at 99% matches Book of 99 but requires supermeter strategy. No mainstream video slot exceeds 99% without conditions.
Why do some sources claim Ugga Bugga is the highest? Because 99.07% > 99%. Technically correct. But Book of 99 is the highest-RTP mainstream slot in active circulation.
Does Book of 99 work for wagering clear at all casinos? Check terms. Many casinos exclude or reduce contribution for high-RTP slots specifically. Confirm before relying on it.
Are these RTP figures certified? Yes — all titles in this comparison are certified by GLI, iTech Labs, or eCOGRA. Math is published and audited.
Can casinos rig RTP to be different from what's published? No — they can deploy different RTP variants that the studio publishes (e.g., Book of 99 in a 96% variant). But within a chosen variant, RTP is locked.
Are progressive jackpot slots ever higher RTP? Some niche progressive slots claim higher RTP including the progressive contribution, but the base-game RTP is usually low (88-92%). Book of 99's 99% is base-game RTP, not jackpot-inclusive — a much cleaner comparison.
About this comparison
Tested across April-May 2026 at the four featured AU casinos plus separate venues for NetEnt and Playtech catalogue verification. RTPs cross-checked at SlotCatalog, AskGamblers, and provider product pages.
Gambling responsibly. RTP comparison is useful information; it's not a winning system. All these slots are still expected-loss games over time. Set deposit limits before depositing. AU support: gamblinghelponline.org.au · BetStop · 18+ only.
Further Reading
Related reading in this guide: