This is what I use:
Originally Posted by robertahilljr
OpenProj is an open source project management software intended as a complete desktop replacement for Microsoft Project, being able to open existing native Project files. It was developed by Projity in 2007. OpenProj runs on the Java Platform, allowing it to run on a variety of different operating systems.
Also you are going to need to install the actual Sun Java PPA from this list to get it to run:
wget http://nchc.dl.sourceforge.net/sourceforge/openproj/openproj_1.4-2.deb && sudo dpkg -i openproj_1.4-2.deb