Big wall of text incoming... you have been warned!
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So there are two
very distinct cases here - slots
with stored value and slots
without stored value.
The latter is the easy one, and the default scenario people think of. No stored value means every spin is independent and random. No memory, no problem.
The former is the interesting and more relevant one here -
but we need to split games into three parts:
The Fakes
- Slots that infer store value, but are lying or misleading - and will explicitly state as such in the game rules, using nonsensical statements like "purely for visual entertainment"
- Examples include many "three pots" games - although for clarity, 333 Fat Frogs mentioned above is half and half - the "growth" of the frog is fake (the nonsensical statement above is actually from that slot), but the collection part could be "real" depending on whether the slot adapts to the bonus trigger or not.
The Unlockables
- Slots that unlock - whether temporarily or permanently - a different or enhanced game mode.
- This may include a marginal increase in RTP, but often is a change in volatility instead.
- Examples include the IGT "Level Up" series, Microgaming's Immortal Romance, Push Gaming's Wild Swarm 2 and Red Tiger's Dynamite Riches
The Collectables
- Slots that allow a player to build up / collect stored value - whether that be progress saved on the reels (e.g. persisting wilds or scatters), progress towards a bonus round (whether guaranteed or not), or money to a genuine progressive pot.
- This will - assuming the provider has done their maths properly - be fully costed into the RTP, so any adjustments to stake or playstyle should be accounted for.
- The amount of RTP attributable to the collection can vary - some will be under 1%, some can be more than 10%
- The duration of the collection can similarly vary - some will be linked spins (so next 1-5 spins) and some can be over thousands of spins.
- There is a risk of permanent RTP loss here - providers can expire stored value after a period of time (e.g. 180 days), or operators can make system-level changes that cause a reset (RTP change, platform migration, account closure).
- Examples include NetEnt's retired Big Bang (for those old enough to remember), BTG's Kingmaker, Red Tiger's Jewel Scarabs and Relax's Book of 99
There is a
lot of energy in this space, particularly from providers and streamers alike trying to infer behaviour that isn't true. Anyone who has listened to streamers "build up" a Wild Swarm bonus by betting bigger inferring they have an advantage - ignoring the game rules which point out it's a different maths model with a 0.1% RTP increase (so unlock, rather than collection).
That's not to say providers haven't got it wrong either - The Dark Knight Rises and Street Fighter II dropped absolute clangers where they forgot to (in the former) or incorrectly (in the latter) apply stake averaging - which caused a significant increase in RTP as a result. They don't happen often with all the testing going on now-a-days, but happy days when they do