1. Get the tar archive from here.
2. Untar and run "make". You need to have the gnome libs installed.
3. Run "katsudoku". You are presented with an empty board full of numbers ;).
4. Get a puzzle from your favourite newspaper. With a right-click you can set a number in a field.
5. If you can exclude a number in a field, do a left-click.
6. No undos! So be careful or you have to start again (like in the hardcopy version).
7. Solve and enjoy!
Disclaimer: This software was written on a dull day off work and is published under the GNU Public Licence (GPL). Do whatever you want as long as you publish your modifications, but I cannot be hold responsible for anything.
Feel free to send an email to: stefan AT katletz DOT at