ha-prosper is described as 'HA-prosper is a patch for prosper that adds new functionality to prosper based presentations' and is an app in the Office & Productivity category. There are more than 10 alternatives to ha-prosper for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and iPad. The best alternative is LibreOffice - Impress, which is both free and Open Source. Other great apps like ha-prosper are Microsoft Office Powerpoint (Paid), Google Slides (Free), Sozi (Free, Open Source) and Apache OpenOffice Impress (Free, Open Source).
Takes a few hours to catch on, but makes the most professionally typset documents with a large number of amazingly useful features not available from other types of presentation software. For presentations, consider the Beamer or Prosper document class.