Microgaming: A Pioneer in Online Slots
Microgaming is widely credited as one of the first companies to develop online casino software, launching their platform in the mid-1990s. Their slot library spans hundreds of titles across all themes and formats, and they remain a benchmark provider for RTP comparison. Understanding the RTP spread across their catalog helps illustrate how vastly different games can be — even from the same developer.
The RTP Trade-Off: Progressive Jackpots vs. Regular Slots
The single most important RTP distinction in Microgaming's catalog is the difference between progressive jackpot slots and regular fixed-payout slots. Progressive jackpot games like Mega Moolah have notoriously low base RTPs because a portion of every wager feeds the jackpot prize pool.
| Game | RTP | Type | Jackpot |
|---|---|---|---|
| Mega Moolah | 88.12% | Progressive Jackpot | Yes (often $1M+) |
| Thunderstruck II | 96.65% | Regular Slot | No |
| Immortal Romance | 96.86% | Regular Slot | No |
| Book of Oz | 96.50% | Regular Slot | No |
| Avalon II | 97.12% | Regular Slot | No |
| Mega Moolah Isis | 88.12% | Progressive Jackpot | Yes |
Mega Moolah: Low RTP, Life-Changing Jackpots
Mega Moolah's base RTP of 88.12% is significantly below the industry standard. This is not a hidden fact — Microgaming is transparent about it. The reason is structural: every spin contributes a fraction to the progressive jackpot pool, which can reach into the tens of millions. The jackpot component effectively adds "hidden RTP" that only materializes for the jackpot winner.
For the vast majority of players who never hit the jackpot, the experienced RTP is essentially 88.12%. This is a critical consideration when choosing whether to play Mega Moolah for fun or as a regular gaming choice.
Thunderstruck II: The Classic High-RTP Alternative
Thunderstruck II is one of Microgaming's most enduring regular slots, based on Norse mythology and featuring four distinct free spin chambers that unlock over time. With a 96.65% RTP, it offers a much stronger theoretical return than Mega Moolah.
- 4 Free Spin Features: Valkyrie, Loki, Odin, Thor — each unlocking progressively after more scatter triggers
- 243 Ways to Win format across 5 reels
- Max Win: Up to 2,400x stake in the Thor free spins feature
- Volatility: Medium-High
Immortal Romance: A Fan Favorite with Strong RTP
Immortal Romance sits at 96.86% RTP and follows a similar structure to Thunderstruck II with its four-chamber Wild Desire and Chamber of Spins features. It remains one of the most played Microgaming titles more than a decade after its release — a testament to its balanced gameplay and decent return rate.
Key Takeaways for Microgaming Players
- Avoid progressive jackpot slots if RTP is your priority — Mega Moolah and similar titles sacrifice RTP for jackpot potential.
- Avalon II and Immortal Romance are strong choices for players wanting 96–97%+ RTP from a trusted developer.
- Microgaming's classic library (pre-2020 titles) tends to feature more transparent, consistent RTP values than many modern releases.
- Always verify RTP in-game — Microgaming, like all developers, allows operators to configure adjusted RTP versions.
Conclusion
Microgaming's catalog is a tale of two categories: low-RTP progressive jackpot games with massive prize potential, and solid mid-to-high RTP regular slots like Thunderstruck II and Immortal Romance. Knowing which category a game falls into before you play is the foundation of informed slot selection.