From Halopedia, the Halo wiki
Prodigy is an achievement in Halo: Spartan Assault. It is unlocked by a player earning their first gold star in an operation mission. The achievement is worth 5 Gamerscore on Xbox 360 and Windows systems, and 10 Gamerscore on Xbox One. It is represented by a circle with a glowing star.
If previously unlocked on another device, this achievement will unlock on the Xbox One the first time the player signs in. On the other platforms, the player will have to play one mission and earn a gold medal to unlock the achievement.