Update: Also North America – IronFall Invasion temporarily pulled from the European 3DS eShop
Update: IronFall Invasion has also been removed from the North American 3DS eShop, likely for the same reason.
Announced via one of Nintendo’s Twitter accounts, IronFall Invasion has been temporarily removed from the European 3DS eShop. It will likely be re-added to the digital store at some point in the future.
IRONFALL Invasion is temporarily unavailable on Nintendo eShop. Apologies for the inconvenience. Stay tuned for more information.
— Nintendo of Europe (@NintendoEurope) August 11, 2015
Nintendo didn’t say why IronFall Invasion was removed from the eShop, but the reasoning is pretty clear. It was recently revealed that the download could be used for homebrew on 3DS.