I love candy box-likes and this was a fun one to go through. (I guess I missed the original the first time I was interested in these.)
It's paced nicely and doesn't have any extremely obnoxious time walls, although I did set up autoclickers to search sand and kill rats automatically while I went and did other stuff for a few minutes. It might be nice to allow those two tasks to be done automatedly. The combat balance is a bit odd, since it seems pretty necessary to beat up the training robot, a lot, for extra damage, which gets tedious and isn't autoclickable. Scaling the rewards and difficulty of the training robot faster might help with that. (But it would also be easy to go infinite like that, because you go first with the attack cooldown upgrade. So it would probably be necessary to make the training robot faster as well to enforce a softcap of damage you can get from it.)
And as unique as Candy Box 2's platforming made it, I'm glad that's not an idea this game kept, because it was really hard to manage, as essentially an extremely clunky auto-runner.
I am unsure if you plan to add any extra content to this or not, but it is a bit disappointingly short as is. The final boss is a decent capstone at least, you need a good amount of strength to beat it but not so much it's annoying. It would probably be hard to increase the power much past that point without ways to get scaling, because it would turn into a huge grind. So it's not a bad stopping point either.
I do not know what was you and what was the original developer, so I haven't tried to separate the two in my comment. Have you considered simply using this engine to do your own thing, if that's something the original dev would be okay with?