The Reference You Can Trust
House Edge Encyclopedia is a free, in-depth reference covering slot machine mechanics, bonus systems, and probability concepts — all explained clearly, with no bias and no paid placements.
What You'll Find Here
Dive into our structured library of gambling mechanics. Each entry explains how a system works, its mathematical foundation, and where it appears in practice.
From classic 5×3 grids to Megaways™ engines with up to 117,649 ways — understand how the reel structure shapes every spin outcome.
ExploreLearn how cluster pays replace traditional paylines and how cascading reels create chain-reaction wins within a single spin.
ExploreSticky Wilds, Expanding Wilds, Walking Wilds, Shifting Wilds — each variant manipulates the grid in a distinct and calculable way.
ExploreThe respin loop mechanic that collects coin values in fixed positions until either a full grid or three respins are exhausted.
ExploreFree Spins rounds, their triggers, and the mathematics of purchasing direct bonus access — including expected value analysis.
ExploreFixed multipliers, win multipliers, and jackpot contribution mechanics — how jackpots grow and what triggers their release.
ExploreOur Philosophy
House Edge Encyclopedia exists to demystify gambling mechanics. Every article on this site is written from an analytical, mathematical perspective. We do not operate casinos, accept advertising from operators, or promote gambling activity.
Understanding how a mechanic works is not the same as endorsing it. Our readers include academics, game developers, regulators, journalists, and curious individuals who simply want to know how these systems operate.
No casino or software provider pays to appear here. Content is selected and written editorially.
Every mechanic description is verified against published game mathematics and provider documentation.
Complex probability concepts are explained without jargon, using diagrams and step-by-step breakdowns.
Popular Entries
| Mechanic | Category | Introduced by | Key Feature |
|---|---|---|---|
| Megaways™ | Reel Engine | Big Time Gaming (2016) | Up to 117,649 ways per spin; variable reel height |
| Cluster Pays | Payline Alternative | NetEnt (2012) | Groups of 5+ adjacent matching symbols pay |
| Avalanche / Cascading | Reel Animation | NetEnt (2011) | Winning symbols removed; new ones fall into place |
| Hold & Win | Bonus Round | Playson / Blueprint | Collect coin values over 3-respin cycle |
| Infinity Reels™ | Reel Engine | ReelPlay (2019) | Reels expand infinitely on matching symbols |
Free Encyclopedia
Every entry is free to read, with no registration required. Our goal is to make gambling mechanics accessible to everyone.
Open Mechanics Library