Bingo Cash, made by Papaya Gaming, and Blackout Bingo, which runs on the Skillz platform, sell cash entries into bingo games that are scored rather than simply won. You play a round, the app scores it, and your score is ranked against other entrants; the top finishers split a prize pool built from the entry fees. Both companies present these as skill games. Papaya's terms say "The Services may not be used for any form of gambling", and a US court opinion records that Skillz "is not a licensed gambling business and does not intend to become one".
Asynchronous matching
Your opponent is usually not playing at the same moment. Skillz says most matches are asynchronous: both players get the same game with identical variables but play it at different times, and entries that never find a match are refunded after 7 days. Papaya's terms warn that your opponent may play "earlier or later than you", and its "Extra Play Tournaments" can reuse your score for up to 30 days. You never watch your opponent play, which is why the bot question below matters so much.
What the app keeps
Neither app publishes its cut of entry fees. The one firm figure comes from a federal court opinion, worked through in the example on this page, where Skillz keeps $0.20 of a $1.20 two-player pool. Skillz's opt-in All-Star League takes a further 2% of winnings on entries from $0.60 to $120. Papaya bonus funds can pay for entries but cannot be withdrawn, and prizes from entries paid partly with bonus funds may come back partly as bonus funds.
Location and ID checks
Skillz uses the phone's GPS to confirm you are somewhere cash tournaments are allowed; elsewhere you get only virtual-currency play. Papaya can verify your name, address, age and payment methods at any time and may ask for government ID, and ID and payment details can be required before a withdrawal. Have documents ready before playing for amounts you would want to cash out.