From what it sounds like, it being an online game is just a cover, and the real purpose of the project is to create sentient AIs. They're using the "game" as a way to feed natural-yet-controlled human interaction into the system without dumping the contents of the internet into the system (we all know how that usually turns out).
When they shutdown the game portion the current AIs will most likely only have contact with each other, newer AIs, and specific staff members meant to monitor them from inside the system.
