You play with 10 credits per spin and for that you can win on 20 paylines. You can bet up to a maximum of €50 per spin and you can already play from €0.10. Playing with €0.10 per spin means you are playing with credits of €0.01 each. If you play with €50 per spin, you are playing with credits of €5 each.
The Mask is a WIld symbol and also pays up to 150 credits per combination. That means €1.50 if you play with €0.10 per spin and €750 if you play with €5 each. The bumbling office clerk Stanley Ipkiss - played by Jim Carrey in the film - is good for up to 100 credits per combination. Tina Carlyle, the nightclub singer played by Cameron Diaz, pays 75 credits if you spin this symbol five times on one of the 20 paylines. Help and support Milo is good for a maximum of 50 credits.
Other symbols include five playing card symbols, a hat and a bag of money.

Every spin, so also during the base game, a feature can appear (completely randomly). There are four different Wild features in The Mask:
Alarm Block feature: you get a Wild symbol of 2 by 2.
By the Horn feature: The Mask appears and blows a horn. That gives you extra Wild symbols, up to four reels with Wilds!
In a spin feature: The Mask appears and causes a whirlwind. This whirlwind changes from three – randomly selected reels – all symbols (except scatters and Stanley) to Wild symbols.
Mask Unmask feature: the dog Milo appears and places a colossal 3 by 3 Wild symbol on your screen.
Winning in the base game is especially good when these features appear. The features are put together in such a way that they almost always yield a nice price.

Congo Bongo is the seedy nightclub where Stanley first sees Tina. It all happens in the Congo Bongo and that is no different on this machine. In this The Mask slot machine Congo Bongo is the bonus symbol. Three times Congo Bongo gives you 10 free spins. You can unlock up to 25 free spins and that happens when you spin Congo Bongo five times.
The base game is already fun with all those features that can pop up randomly. The free spins are even more fun. You play with a random multiplier that can go up to X5 if you take a win with a Wild symbol. The features also fall more often during the free spins.
As if that weren't enough, you can also re-trigger the bonus spins indefinitely by spinning at least three Congo Bongo symbols. And fewer bonus symbols still give you free spins: a minimum of two extra and a maximum of five extra.
You can grab up to 15,000 credits per bonus spin! That is a maximum of € 75,000.