The category includes a lot of music from different gaming websites that focus on music. Some of the websites are Day and SneakyZebra, which are both very known gaming communities. Spotify finds different songs from these sources, combines them into playlists, and delivers to the category.
The update should automatically appear on all devices supporting Spotify, without the need to download anything. This is a server-side change and requires no updating of the app itself.
Download Spotify for Windows Phone below and desktop here.