Whether it’s a weekday morning or a weekend night out, cheers on the second floor of The D Las Vegas can often be traced to one machine: Sigma Derby.

“It’s like Tuesday at 8 a.m., and you’ll hear a loud cheer. It’s quiet – normally people are still asleep – so you’re like, ‘Oh, that’s gotta be Sigma Derby,'”‰” said Rahmi Chaghouri, director of operations at the D, Circa and Golden Gate casinos.

Horse-racing slot games have long been in casinos, near sportsbooks and even in the homes of super-fans. At 35 years old, the D’s Sigma Derby is the last gaming machine of its kind in Vegas and one of the last, if not the last, such machine elsewhere, Chaghouri said.