The words "You win!" flashed on the screen and the punter celebrated.
But seconds later, police officers burst through the door, and the fun ended for patrons at an illegal gambling den in Petain Road, near Serangoon Road.
Computer terminals were seized and cash was confiscated.
The police operation, which started around midnight on Friday, saw seven men and three women, aged 44 to 64, arrested for offences under the Common Gambling Houses Act.
The raid covered two gambling dens in shophouses in Petain Road and Jalan Besar.
A total of $5,469 and 27 computers were seized and investigations are ongoing.
Gambling dens today do not always fit the stereotype of crowded rooms with games like mahjong, baccarat and big-small.
Instead, they have rows of computer terminals and look like cyber cafes.
At some dens, like the one in Petain Road, card and table games are not allowed.
A sign also reminds the patrons: "Table and card games, please don't gamble."
Gambling dens today do not always fit the stereotype of crowded rooms with games like mahjong, baccarat and big-small. Instead, they have rows of computer terminals and look like cyber cafes.
Instead, punters try their luck at online jackpot games, eager to make a quick buck.
They usually find out about such places through word of mouth.
Closed-circuit television cameras are usually installed at the entrances of the dens so that operators can keep a lookout.
Typically, patrons exchange cash for online credits and are allowed to choose from jackpot games with themes like "Lucky Panda" and "Sherlock Mystery".
The Sunday Times understands that the lure of such dens lies in the fact that punters are given more credits there than they would receive if they played the game at home - giving them more chances to win extra credits, which they can exchange for cash.
In Petain Road, nine people - including the 58-year-old den operator - were arrested for illegal gaming offences.
It is believed that the place had been under surveillance for weeks.
Situated in a shophouse with residential units, the gambling den had gone unnoticed by most.
A 46-year-old private-hire driver, who gave his name only as Mr Wong, was shocked to learn that the gambling den - located right below his girlfriend's home - had been operating for a month.
He said that the door was always closed, and he had never noticed any noise coming from the ground-floor unit, even on weekends.
Over at the Jalan Besar den, the operator was just about to shut for the day when police closed in at around 1am.
No punters were caught, but the police arrested the 64-year-old den operator.
Those convicted of managing a place that is being used as a common gaming house can be fined up to $50,000 and jailed for up to three years.
Punters can be jailed for six months and fined up to $5,000.