Update 2:15pm: This article was updated to add a more detailed explanation of Daydream SDK additions.
News that Google had cleared Lenovo's Moto Z and Moto Z Force for Daydream was cause for celebration. Users who had already purchased a great phone were being granted access to Google's new VR platform without needing to buy new hardware, and the existence of Moto Mods meant you could strap a massive battery to the back of your Moto phone and enjoy Daydream for much longer than any other phone. Google's vision for Daydream, a platform that delivers high quality VR to many people without requiring a specific brand, seemed to be coming true faster than originally expected.
And then I actually used a Moto Z in Daydream.
For the most part, Daydream on the Moto Z works exactly like it does on the Pixel and Pixel XL. You have to move the phone around a little on the backplate to Daydream View to get the NFC tag to launch the Daydream app in Daydream mode, but you could just as easily launch the app yourself without the tag. You pair the Bluetooth Daydream Controller to your phone, and it's time to get started with Daydream. The same apps and games are available, and everything I purchased through my Pixel was available to install on this phone. It's great, until you start one of the more complicated games.
Action Bowl, Danger Goat, and Fantastic Beasts all looked and ran like you'd expect. Google's requirements for Daydream include delivering a consistent 60fps experience, and that's what each of these games seemed to deliver. Drift, on the other hand, was not the same experience as what I'd enjoyed on the Pixel. Turning in the game felt jarring and uncomfortable, almost as though frames were being dropped. A little testing revealed that was exactly what was happening. In Drift, and several other high performance games, the Moto Z was unable to maintain 60fps consistently during gameplay.
These are slight differences in overall performance, but in VR a consistent frame rate is incredibly important. A couple of frames dropped every second, or even every other second, is enough to cause disorientation in some users and severe nausea in others. A consistent frame rate is arguably the most important part of a successful VR experience, and right now the Moto Z can't deliver that with every Daydream app. This isn't an easy fix. Even with the Moto Z fully wiped with nothing else but Daydream and this one game installed and running, this performance issue exists.
There are a couple of reasons this phone could be unable to meet this performance threshold. Internal temperature is always a concern with phones, and Daydream will absolutely cause your phone to heat up. In this situation the frame drops start as soon as the game starts and not after a period of use, so it's unlikely to be a thermal issue. Instead, it looks there's just enough difference between the output of the Snapdragon 820 and Snapdragon 821 to cause this small performance gap. On the Pixel XL, Drift is able to use 18-19% of the CPU. On the Moto Z, Drift has access to 14-15%.
There's the potential that Drift and others just aren't as optimized as they could be, and an update from the developer could offer a smoother experience. Many Daydream apps have updated more than once since the initial launch to add features and fix bugs, as well as support updated versions of Google's Daydream SDK. It wasn't until the most recent updated to the SDK that Google addresses async reprojection on phones that aren't the Google Pixel, which would also explain what is being experiences in Drift. This presents a separate significant problem for Google, if it ends up being software to blame and a simple update can make this game behave identically on every phone. If every Daydream experience isn't identical, the platform loses the most important point in its efforts to compete with Samsung's Gear VR.
Samsung knows for a fact that every Gear VR experience is identical, because the platform is limited to high end Samsung hardware. Daydream is extremely close to being able to say the same thing, but this early stumble needs to be corrected quickly and not happen again in order to built the kind of trust necessary to convince consumers Daydream can compete with the Gear VR.