For all Windows 10 users there’s the possibility to test the new Office 2016 Touch Preview. This version, as you know, is optimized for touch screen with large button and a better UX. The idea is have the same interface for Windows, iOS and Android.
Office Touch will be released with the final version of Windows 10 but also for Windows Phone 10. In this moment is not really clear if the products will be released also for Windows Phone 8.1 but few weeks ago Microsoft has promised a new update for their mobile users.
Word Preview: https://www.microsoft.com/en-us/store/apps/word-preview/9wzdncrfjb9s
PowerPoint Preview: https://www.microsoft.com/en-us/store/apps/powerpoint-preview/9wzdncrfjb5q
Excel Preview: https://www.microsoft.com/en-us/store/apps/excel-preview/9wzdncrfjbh3