She's a slender, cloaked woman wielding an oversized weapon.
Her weapon is a giant rectangle with a hole poked through the middle of it, but this time it's a gun instead of a sword.
The weapon absorbs the souls of the things it kills to empower itself.
Senna can become a wraith and traverses a spirit realm similar to Transistor's alternate digital realm.
She has narrative about her and a loved one combating evil captors.
The evil corrupting the Shadow Isles is quite similar in concept to the Process corrupting the Cloudbank, in that they're plagues that resurrect the dead and change the scenery and somesuch.
Really, the only differences I see are the color pallet and the sort of game they're in. Visually, thematically, and narratively, they feel the same.
Senna = Red from Transistor.