Getting the balance for the last level was tricky, and we've had a few people getting frustrated with it so we'll bear that in mind for the sequel. Thanks for the feedback. :-)
For what it's worth, I thought the last level was pretty good overall. Obviously there are others who disagree, but I found the difficulty to be fitting for the final boss without being overwhelming.
The most difficult balance issue to me was that there aren't many ways a player can make up for past mistakes between stages. For instance, a player who spends a long time on stage 3 of any of the areas and ends up leaving with only a single hit point remaining will have to complete both stages 4 and 5 flawlessly in order to proceed. A player who didn't anticipate the final boss battle and thus shows up with low health and few or no items could be in for a really rough time compared with someone who got a few elixirs ready in advance.
Full health restoration between levels would be too much, I think. Maybe bringing the player's health up to a certain point (say, half) if they're beneath it between levels would be okay? That might be more forgiving than you want to be though, since letting the player's mistakes have long term consequences is not *necessarily* a bad thing. You could let the player visit the shop between levels, but I kind of like the need to prepare for the long excursions ahead of time.
One solution you could try would be to allow the player to return to the shop whenever they want to (or in the beginning/ending of any level), but doing so means they would have to, but doing so would mean they have to start at level 1 of the current area again. This would allow the player to never be truly stuck at any point in the game. It would also allow them to grind money and experience until they're ready for anything in the game, which you may or may not want to allow. Maybe it could cost some money/exp to do so that's less effective? Or it sets their money and exp to whatever it was when they first encountered that shop? I'm just throwing ideas out there.
And Inanimate, it sounds like you just got really unlucky. Sorry I couldn't help.