Nairobi, May 6 -- On a Friday or Saturday night, in most of Nairobi's creme de la creme nightclubs, everything hinges on one question. Will the place be packed?

Like in any business, numbers run the show. On a good night, the city's swankiest clubs rake in around Sh3 million in sales, and with sharper marketing, that figure can climb to Sh9 million, BD Life has established.

A few years ago, Happy Hour was the magic trick. Clubs leaned on it heavily to keep seats filled and drinks flowing.

Discounted drinks drew crowds early and fast. But the spell didn't last. Due to competition, some venues began cutting corners, using cheap liquor to stretch margins, and the craze faded almost as quickly as it rose.

The scene adapted. Nightlife move...