In Microgaming’s Electro Bingo, bet $1 to $5 per card on four cards of 15 numbers apiece, drawn from a stock of 1 to 60. Thirty balls are drawn and 14 different patterns formed on the cards earn a payout.
After the 30 balls are drawn and payout (or none) determined, an extra ball will be offered if any of the player’s cards are one spot away from completing a bingo (and thus winning some bucks). The price for an extra ball? Well, that’s random, so you’re probably better off springing for the cheapies when offered. Up to ten extra balls may be bought in all.