A 'game within a game' that takes place on a separate UI, such as 'Pick and Win', instead of on the spinning reels.

A core bonus round where you can spin the reels for free without using your balance, often with powerful extra features activated.

The 'ultimate grand prize' in a slot, offering a payout on a different level from regular wins.

A 'key' symbol that triggers core bonuses like free spins by appearing scattered anywhere, regardless of paylines.

Any optional feature that allows the player to pay an extra cost to directly intervene in the game's rules or probabilities.

Any mechanism where the reel's form or symbol composition changes further even after the spin has stopped.

Any symbol that has a unique 'ability' to drive the flow of the game and create dramatic events.

All the rules that define wins in new and diverse ways, going beyond traditional paylines.

Any feature that expands the value of a single bet by changing the number, cost, or nature of a spin.

A feature that acts like a joker in poker, substituting for other regular symbols to complete winning combinations.