Steam codes have been emailed to participants ahead of an October 5 start date, 1UP reports.
Play testing will run nightly, between 7pm and 12am Eastern Standard Time, until October 9. As the beta is closed, participants will not be able to disclose any information about the game.
Impostors is a dowloadable multiplayer shooter set in DC Comics' Batman universe. It pits a team of Caped Crusader impersonators against a band of Joker henchmen in objective-based game modes.
The five-day beta is exclusively for the PC version of the game. Selected participants are able to download a client now, though it will not be accessible until next week.
Gotham City Impostors will be available through Xbox Live, PlayStation Network and Steam next year.
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