Nice effects, specially the vertical lava and the tubes.
I'm sure you know about those problems:
1. The game can't find textures:

2. The "levelshot" image (displayed in the map-loading screen) is not being displayed maybe because it's named tumbo7.jpg instead of tumbo7_0-1.jpg
3. Extremely big package size. I think you can reduce it by converting some .tga into .jpg, especially the ones that don't use alpha channels, or by reducing .jpg quality a little bit (what doesn't really matter, as the engine can't render at full quality).
4. Many mirror-effects:


etc.
Look this crazy room! So nice! lol

Jump and die:
