Many gamers say they are torn between Minecraft and Roblox because both games have millions of players at a time.

Despite their similar blocky and colorful appearances, Roblox and Minecraft are two radically different games in terms of gameplay and price structure.

With 12 million users last month, Roblox lets people create their own virtual immersive experiences, like modeling in a fashion show or making pies at a pizza parlor. Users buy virtual currency ...