Virtual-reality design firm Unity Software Inc. U, +3.18% on Monday said it planned to lay off around 1,800 employees, or 25% of its staff, amid efforts to focus on its core business. The company, whose software is used by the film and videogame industries, said it expected the dismissals to take place largely in the first quarter, but said it couldn’t yet estimate the costs for things like severance and employee benefits. Monday’s announcement comes after the company in November said it planned to close o ...