In Bingo Reactors, only certain numbers are in play; the balls themselves are adorned with references to bingo slang, e.g. the 8 ball is graced with “one fat lady”, no. 11 sports a pair of “skinny legs,” and ol’ 21 is of course “the key to the door.”
After choosing a stake between 25p and £1000 per card, 25 balls fall into place in Bejeweled fashion; adjacent like balls disappear from the card as a payout, based on the number of balls and the value of the winning balls themselves (“sweet sixteen” is the highest-paying, for example).
And that’s about all there is to it … as the game itself wishes you in big bold letters, “Good Luck!”