I love this. While in undergrad I taught high schoolers video game development. As part of their final project they had to design and program a game with express purpose of slowly helping kids with selective mutism feel comfortable communicating. It was a multiplayer game through network, but both players didn't interact at all in the beginning. Slowly levels became more challenging until teamwork was required. My students only completed a demo of the game, but it was displayed in Liberty Science Center for a day.