As of now, with the release of SuperTux 0.6.1 (December 2019), the Forest World is almost finished, since the ghost forest section has been included. However, some levels, especially the Ghostree Level, are considered to be placeholders, because for the next version (0.7.0) a great overhaul is planned with new features like reworked boss fights, graphics, and worlds. If you have some Constructive Feedback, Contributions or ideas to share, don't hestitate to contact us with one of the possibilities given above.
Yes, the next update likely will overhaul many things, and might add some new features! Feel free to discuss this here.
