Abacusmine is here since 2014 and it is the first commercial Redmine theme that has brought UX improvements such as a collapsbile sidebar, global Issues & Spent time in the top menu, or collapsible project list.
The RedmineX UX Upgrade is not just a theme. In fact, it is much more than a theme. It brings about 20 UX / UI improvements such as a vertical menu, new entity button, quick issue edit, up to 50 issue on MyPage, or the possibility to upload your company logo. However, if you do not fancy the theme, you can still make use of the 20+ UX improvements together with Abacusmine.