Two new concepts:
Difference - pupils of eyes. I made attempt to make them larger, but I was made it a bit crookedly which need more edits of shape:


Updated concept:

Old stuff:
These are my small sketches for a new logo:

And this:

It will be better IMO if the project has it's own mascot.
Q: I don't see the point of a "cat <=> platformer" ...?
A: Don't get it? I found this little game here:
http://wohlsoft.ru/docs/_files_for_posts/Logo_2/SuperCatrio.swf
(note for this little game: The 8th level is impossible to pass, because it has a bug with the camera, and your character always will die even if he has solid ground underneath)
I'll leave the mushroom logo with the editor part, but for the project and engine part I think this could be used as a new logo / icon.
P.S. Also available the desktop backgrounds:
http://wohlsoft.ru/docs/Images/Logo_bgs/