"Mess With The Bull, Get The Horn," by Michael Terlecki, in Destination: Mystery, edited by Andrew MacRae, Dark House Books, 2015.
Thomas Gavel had a dream job designing slot machines. Things go wrong when he visits Las Vegas and gets suckered in a high stakes poker game. The bad guys say all he has to do to pay off his debt is design a slot machine they can use to get rich with. But the casino guys will catch any kind of payout pattern. Can he do it?
The moral of the story is: don't mess with engineers.