This is an open source launcher for Europa Universalis 4 based on QT4. This was forked from westonmyer's Qt-CK2-Launcher.
Thread on Paradox Plaza
sudo apt-get install git build-essential libqt4-dev qt4-qmake libqtwebkit-dev
git clone https://github.com/alfonsojon/Qt-EU4-Launcher.git
cd Qt-EU4-Launcher
qmake-qt4
make
Note- Launcher is fully compitable with Steam overlay and DLC activation.
- Run Steam and open "Library" window.
- Right click on EU4 in game list.
- Click on "Properties"
- Click "Set launch options..." button
- Input "qteu4launcher %command%" and push "Ok"
- Now launcher will work like the Windows version.