From Halopedia, the Halo wiki

50 Gamerscore icon taken from Originally a single block colour (with the two circles both being white and the 'G' a transparent cutout), but modified by myself to display nicely on dark *and* light themes, and to be reminiscent of the pre-Xbox One gamerscore icon.

Terminus is an achievement in Halo 4 and Halo: The Master Chief Collection. It is awarded for finding all the terminals in the Halo 4 campaign. The achievement is worth 50 Gamerscore in the original game and is represented by a symbol similar to the Didact's.[1] In The Master Chief Collection it is worth only 20 Gamerscore and is represented concept art of a Forerunner monitor or ancilla in the Xbox art.