Microsoft patents drop-in split-screen
In "squad-based shooter".
Microsoft now owns the patent covering split-screen seamless drop-in and drop-out co-op.
Patent 7,559,834 (spotted by Kotaku) refers to you "dynamically" joining or leaving an "in progress" game, "Without the players having to save and restart."
When you join, the patent adds, you are assigned as a squad member and the "screen is split to present a viewing panel" for you. And when you leave, the AI takes the reins and the screen is "un-split" to become whole again.
The patent refers to a "squad-based shooter" and is adorned with sketches that appear to be from Xbox game Brute Force.
Microsoft has yet to comment.