Qnonogram is free of charge and contains no advertising. It is
based on the platform independent framework qt, so it could be
run on Linux, Windows, Mac and supported mobile operating
systems. So far there are no binary builds that you can just
install and run. Only the source code is available. You are
invited to step in and build an package for the system you use.
If you run gentoo linux you can use the provided ebuild. Check
the section "get qnonogram".