Many stores promote a new video game by offering something extra, such as exclusive downloadable content or some sort of promotional gift. At GameStop it turns out you don’t get something extra — you get something less.

The PC edition of the newly-released Deus Ex: Human Revolution contains a voucher that allows buyers to play the game free of charge through OnLive, an online gaming service. It’s a promotional tie-in designed to encourage players to give the service a tryout and potentially sign up to play other games.

Unfortunately if you buy at GameStop, you aren’t getting the voucher. That’s because management have issued a memo ordering staff to open every copy, take out the voucher and toss it in the trash.

Confronted with the memo, GameStop confirmed the policy and later explained ” We pulled the coupons because, like all retailers, we prefer not to promote our competitors and their competing offerings and services in our stores. Unfortunately, the coupon was packed without our prior knowledge.”

It’s reported GameStop is working on its own online gaming service, which explains its rationale for the move. But you do have to wonder how far that logic can go. If the voucher had been printed in the game manual, would GameStop have asked staff to tear it out?

And would such tactics be considered acceptable elsewhere? If a magazine contains a voucher for a free trial of an online subscription to a digital edition, would newsstand operators be justified in removing the voucher before putting the issue on the shelves?

While GameStop’s logic may make sense, I think it’s crossed a line here. It’s one thing for a company to refuse to actively go out of its way to promote something that may be seen as competition. But in this situation it wasn’t asked to make any additional effort, and instead has actively worsened the experience for its customers.

UPDATE 2011-08-26 21:04 EST: Since we wrote this story, Gamestop has announced users who bought the game only to find the voucher had been removed will receive compensation in the form of a $50 gift card and the option to buy two used games for the price of one. It’s also issued a statement to customers noting “We regret the events surrounding this title release and that our customers were put in the middle of this issue between GameStop and Square Enix, the publisher of this game. And for this, we are truly sorry.”