Unidentified internal Halo prototype
From Halopedia, the Halo wiki
An unidentified Halo prototype was worked on by 343 Industries at some point before June 2018. The project was never intended to be shared publicly, existing only as an internal experiment, but a partially-obscured logo for the project was accidentally shown in the background of a 343 Industries recruitment image.
The logo appears to show an unidentified UNSC helmet, with a geometric wing-like pattern of dark grey shapes beneath it, similar to the Misriah Armory logo. In front of the helmet, the standard Halo logo is present, with a stylised subtitle beneath it which appears to begin with the word "STAR", all capitals.