PopCap Games unveiled an experimental label for risky games this week, called 4th & Battery. But the label’s first title, Unpleasant Horse, turned out to be too unpleasant for Apple. Apple rejected the game because of its mature content.

The rejection is surprising because PopCap isn’t just any indie game company. Its games have been downloaded more than 1.5 billion times and the 4th & Battery label was an attempt to allow its game artists to express themselves and stretch their (horse) wings. The rejection is likely to set up a discussion about what kinds of games are artistic versus just plain tasteless, and if Apple should be the judge of that.

“WTF? Apple rejected Unpleasant Horse cuz of ‘mature content?’ We thought horses dying in meat grinders was wholesome family entertainment!,” read a tweet from 4th & Battery.

The label said it was appealing the decision and also proclaimed that it loved Apple and even owned an old Newton (the failed original tablet handheld). PopCap has declined formal comment and has deleted some of its tweets as well. It’s quite possible that Apple will just take longer to approve the game or that there may be something technically wrong with it. Apple and PopCap have not offered any comment this morning.

Others have pointed out that the App Store has a lot of tasteless or mature-rated games, from Call of Duty: Zombies to 5 Minutes to Kill (Yourself). 4th & Battery’s Unpleasant Horse features a flying black horse with red eyes that attacks other innocent-looking flying horses and sends them to their deaths to meat grinders on the earth. It’s a simple animated game, and it reflects the same kind of zany imagination featured in PopCap’s monster hit Plants vs Zombies. But it’s definitely not the sort of family-friendly title that PopCap usually makes, such as Bejeweled.

Ultimately, 4th & Battery will likely find other platforms that are more than willing to take Unpleasant Horse. That would likely be a loss for Apple, which needs the continuing good will of indie game developers to make its platform stand out from the rest.

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