We also contacted Brad Bushman and he confirmed that it's ok for other academic aggression researchers to contact him directly for information about his program (see below).
[edited from support email]
I actually contacted Bushman, who had a programmer create something for him. Fortunately, Bushman is amenable to sharing and has sent me a link to the game. If you have any other clients who ask about this, you can direct them to Bushman.