Greentube

Greentube is the digital gaming arm of Austria's Novomatic Group — officially the "NOVOMATIC Digital Gaming and Entertainment division" — and the studio responsible for bringing some of Europe's most-played land-based slots online. The company traces back to 1998 in Vienna, where it launched as Dürrschmid & Reisinger OEG with the 3D sports game Ski Challenge, was renamed Greentube Internet Entertainment Solutions in 2000, and joined the Novomatic Group in 2010. That acquisition defined its identity: Greentube became the online home of Novomatic's Gaminator-era casino floor catalogue, and its influence on European online slots is hard to overstate.

The flagship is Book of Ra, the Egyptian-themed game whose free-spins-with-expanding-special-symbol mechanic effectively created the entire "book slot" genre that countless studios have imitated since. Alongside it sit the other Novomatic classics — Sizzling Hot Deluxe, Lucky Lady's Charm Deluxe, Lord of the Ocean, Dolphin's Pearl Deluxe and Columbus Deluxe — games that remain staples in the DACH region (Germany, Austria, Switzerland), where Greentube's brand recognition is arguably stronger than any competitor's. The modern portfolio of roughly 400 titles adds contemporary series such as Diamond Link and Cash Connection (hold-and-win style link jackpots), Win Ways mechanics and Piggy Prizes, plus table games, video poker and video bingo. Greentube holds licences from the UK Gambling Commission and the Malta Gaming Authority and has expanded into regulated US states, launching in Pennsylvania in 2025. It was named Casino Content Supplier of the Year at the 2022 EGR Nordics Awards.

For bonus hunters, Greentube's catalogue splits into two camps. The book-style games (Book of Ra Deluxe, Lord of the Ocean) are classic hunt material: high-volatility free-spin rounds where a randomly chosen expanding symbol decides everything, producing brutal dead bonuses or spectacular full-screen hits on 5,000x-scale potential. The pure fruit classics like Sizzling Hot have no bonus round at all — line hits and the gamble feature only — so check the game type before adding one to a hunt. The Diamond Link and Cash Connection series offer hold-and-win respin bonuses as a middle ground.