After writing a level viewer for Turrican II some years ago, I decided to write a level editor for it too. It is bare-bones but you can edit all level tiles and entity placement for all levels.
[ Show youtube player ]
for a playthrough of a modified first level.
GitHub repository: https://github.com/GitExl/Turrican2Editor
Make sure to read the ReadMe
to learn how to actually use the editor, and how to play your modified levels. Turrican II CDTV files are required, which can be copied from any disc or disc image.