Keno with 80 numbers like all the other versions. At least that way you have a realistic chance of catching 9/9 or 10/10 with 20 balls drawn. Hitting 10/10 with only 10 draws is the equivalent of hitting the lottery twice and it's only 1000x. Also have something similar to Bonus Keno or Cleopatra Keno where if you hit the last ball in a winning game you get a bonus or free games. Adding a random multiplier when hitting the last number or a 2x or 4x would add some excitement also with a higher payout ex 10/10 pays 5000x or even a 1000x with a chance to multiply your win if catching the last Keno ball.