From The Official NetEnt Site:
Disco Spins™is set inside a night club with the reels and background acting as a dance floor that lights up with strobe lights.
The Wild symbols appear on the reels when the colour of the Disco Dancer symbol matches the colour of the dance floor tile they appear on. As many as eight Wild symbols can appear at the same time offering players an amazing opportunity for big wins. This Wild symbols feature is integral to the game play and makes it an incredibly enjoyable gaming experience.
What We Think:
The symbol to keep your beady little eye on is the classic mirror ball. When you get the 3 symbols on the middle reels that’s when you get the choice. First choice is 15 free spins with a 3x multiplier. During these 15 free spins you can get even more mirror balls that means even more prizes. Second choice is 10 free spins but with more winning symbols on the reels.
Both are great and the choice, as they say, is yours. Play for free above and get a really good feel for the game.