Highly enjoyable
A simple premise but very well executed, and enough creativity to stop it becoming stale in the dozen or so levels I've gotten through.
I found the puzzles to be a little bit unforgiving - the first level with spikes and the explorer by himself, as I went for the group first, I then couldn't get the individual without starting over. That is the nature of the puzzle though, and the only thing lost is the 'one-try' bonus so I can't really fault it.
Nice one!