Great to hear that you like the game. :) It's made in PICO-8, which has very strict limits on the amount of sprites and code size. That's why I couldn't cram in any more sprites for other areas. Saving was left out to give each run a fresh start. If you spent one run exploring and got all the upgrades then all future runs would no longer be a challenge. See it like a power star in Super Mario. It's awesome to find it, but it's only temporary.