Roblox Corp. Chief Executive David Baszucki won the loyalty of tens of millions of videogamers with a do-it-yourself approach to play that defies the industry’s typical formula for success. Now ...

A parent’s first glance at kids playing Roblox can be bewildering. They steer their little avatars at a frantic clip while tapping out bursts of competitive poppycock to one another via chat.