The Empire (Star Wars); The Imperium (Warhammer 40K); The UCF (Starship Troopers); Mirror Universe Terran Empire (Star Trek); The Alliance (Firefly); Martian Congressional Republic (The Expanse)
Ascendancy attire is modelled on military uniforms - both practical combat wear or formal military attire. The overall look is dark, fitted and severe.
Military characters and groups are likely to dress in military uniform - either overalls or fitted jackets and trousers, with reasonably close-fitting undershirts (plain, non-collared) in white or grey. Colours are mostly dark - black and grey are the most common. Where brighter colours occur, they tend to be block colours consistent across most of the costume (think the bright red uniform of the Emperor’s Guard in Star Wars). Most “military-style” garb should have patches, badges or insignia on the breast or shoulders/upper arms denoting group, rank, etc. Military boots, or knee-high boots are very appropriate.
Non-military personnel wear formal-looking attire, in similar colours to uniforms and with a pseudo-military look. Lines are severe and garments should be tailored close to the body. Large overcoats are also appropriate (for military characters as well). Status and wealth is more likely to show in better tailoring and fabrics than fussy embellishments. Wealthy characters are more likely to wear adornments like jewellery, which tends to be made from a single metal and rarely adorned with stones. Elaborate arm bracers of silver filigree are very fashionable among the aristocratic Houses at the moment.
Ascendancy tech appears similar to their clothing – sleek lines and space-efficient. Colours are dark or metallic, and with reddish light where possible. Wiring is hidden behind panels, but there are visible controls like switches and dials. Their weapons closely resemble modern armaments compared with the other Factions.
See this Pinterest board for an overall impression of the intended look and feel of the Terran Ascendancy.