Apple TV Games Must Work With Apple TV Remote, May Not Require External Controllers
Apple programming guide for tvOS reveals that all games developed for Apple TV are required to support the touch-based Apple TV Remote, making all content accessible to all users without the need for third-party controller.
Your game must support the Apple TV remote. Your game may not require the use of a controller.
The new Apple TV works with third party Bluetooth controllers, but because they are an optional accessory, they are not allowed to be the primary input method for a game. This means that developers will have to build their game with the Apple TV's remote at the forefront of game input, even if their game has a complicated control scheme.
As the original report points out, this could cause some issues for developers:
There will be games that will have control schemes that are too complicated for the remote, for sure. What if Apple rejects apps that feature terrible controls for the remote, designed only to achieve the bare minimum functionality? Or developers with complicated controls decide to skip making their app compatible with the Apple TV because it won't be worth it? Ideally, we don't want to get to a point where games aren't coming to the Apple TV, or being actively rejected, because they won't fit the remote.
Interestingly enough, at some point in the past it looks like Apple did plan on making game controllers a requirement for some games, but it would appear that Apple changed its mind at some point before the public unveiling of the new Apple TV.
— Rusty Moyher (@rustym) September 9, 2015
Apple's choice to require support for the Apple TV is not surprising, as it also has the same requirements for iOS devices. Developers can build controller support into their iPhone and iPad apps, but apps must also include touch-based control schemes for users who do not have a controller.