HTC has been in the Android game since the very beginning, partnering with Google and T-Mobile for the original T-Mobile G1, as well as the Nexus One, and more recently the Nexus 9 tablet. Outside of the products that they've partnered with Google on the Taiwanese firm has used their own software on top of Android, dubbed Sense. For many Android users, Sense will have been their first taste of how flexible Android can be, and while it's evolved a lot over the years, it's still regarded as one of the better software experiences on top of Android right now. With a custom experience like this comes a lot of custom apps, and over the past couple of years HTC has been offloading some of these into the Google Play Store, to make it easier for users to update one small part of their overall experience without having to wait for a larger update.
Some of these apps that HTC has released into the Play Store work with devices that aren't made by HTC, some of which are required to work with devices like the HTC Re camera. At the core of the HTC Sense experience is HTC Sense Home, and there are rumors of the firm looking to get this onto devices made by firms other than HTC, such as the Galaxy S7 or Sony Xperia X, for instance. AusDroid has gotten their hands on an email meant for HTC Preview members that details a project called "GOOGLE_PLAY_SENSE_GP" which asks for Preview members with a non-HTC device running Android 4.4 or above. This is a pretty big sign that HTC is looking to test their Sense Home app on other devices, and there's probably a good reason for this. When the HTC 10 was launched earlier this year, the Sense 8 software experience received high praise, especially the homescreen, which allowed users to place icons wherever they wanted, without needing to stick to a grid.
Offering users a taste of this experience could be a way for HTC to say "there's more where this came from" with the aim to get them to upgrade or switch to the HTC 10 or other HTC smartphone running Sense 8 on top of Android. The below image shows that HTC is testing this sort of thing, but whether or not these tests end up in a real product, remains to be seen.