Microsoft Studio Exclusives characters...
So far I am enjoying this game very much. Ninja Theory has created some awesome characters with interesting designs, lores, abilities, etc. However, I would find truly astonishing to play as Materchief, Senua, Banjo and Kazooie, Battletoads, Gears of War characters, and so on...
It would give Bleeding Edge an <EDGE> pun intended and attract more people to play the game.
Talk to our man Phil Spencer to see what he thinks #BringSENUA
While I agree that a cool guest character could increase the game's visibility, I don't think Halo, Gears or Banjo fit the style of the game at all.
Out of their entire back catalogue I feel like Enslaved's characters fit Bleeding Edge's aesthetic the most. Monkey would be a cool tank, Trip possibly an interesting support. But if I remember correctly neither Ninja Theory nor Microsoft have the rights for that IP unfortunately.