The coronavirus crisis has proved a bonanza for video game makers, as shut-in consumers turn to digital distractions in greater numbers and for longer sessions than ever before.

But while the sector’s big listed groups such as Nintendo, Activision Blizzard, and Take Two have enjoyed share price rises of more than 25 percent since early March, a clutch of mobile gaming studios, many privately held, have enjoyed the real windfall. Along with the sudden rise in leisure time among a ready market of more than two billion smartphone owners, they have reaped the rewards of a plunge in mobile advertising prices as other corporate sectors slashed their marketing budgets.

“That gave a huge opening for companies like ours,” said Alexis Bonte, group chief operating officer at Stillfront, a free-to-play gaming group based in Stockholm whose share price has more than doubled since mid-March. “We got a double effect—the increased organics [usage growth] but also the effect of more efficient marketing . . . It was huge.”