Collapsing reels, also known as cascading or falling reels, is a fairly new mechanic as it was introduced back in 2010 by NetEnt. Staying true to its name, this type of feature is constantly active and is triggered every time a win occurs. The winning symbols disappear while the ones behind them fill the space they leave behind giving the impression that the reels are collapsing.
As mentioned, in order to trigger this feature the player must get a win. This applies to both the base game spins as well as any other ones, during or not bonus mode. In some cases, it may not even require a win as a few random symbols can be chosen and then destroyed thus triggering the collapsing reels feature to kick in. This, of course, depends on the game you’re playing.
After each round, the winning symbols disappear but what happens if another win occurs? Well, the feature is triggered once again, and in general, players are rewarded if they managed to trigger it more than one consecutive time.
If you think this wouldn’t have any downsides then think again. Sure, you can greatly increase profits if you get 2, 3, or even 4 consecutive winning rolls but such games usually come with a low volatility and symbol cost rate. This means that you may go through many rounds until you get a substantial payout and by that time chances are you’d lose more than you get back.
Each developer offers a different version of this feature. This results in the gameplay mechanics being slightly different on each slot. For example, you may get to trigger the feature with each consecutive win applying an increasing multiplier or you might get to win free spins after some continuous winning rounds. Besides, some games only feature collapsing reels only when inside one of their bonus modes while others will increase the size of the reels by one or two blocks on each consecutive win.