You can load backup.lvl then, but yes, it's annoying. Restarting the level instead would be better. Would be nice for collection too...
- How about a strength/mass ratio for objects?
- Density checks should try to find how much of an object is in a dense block, instead of just corners (if I observed that right). There aren't many objects in water after all, so it can't really degrade performance.
- About the char issue with objects: using a short indicating the number of objects and chars or shorts in objects depending on that number would be better than what I said a post ago.