To be honest, I don't see a problem. Well, judge for yourself: the longer you play, the faster you run through the starting levels. And the moment when you get to the 150th without improving the pickaxe is inevitable. Everything depends only on the player's attentiveness, multiplied by his own laziness. There is nothing to remind you about, Scanning will not let the player forget that he did not find obsidian. There is no need to prompt here - from time to time the player must think for himself. There is nothing to fix here because fixing something that is not broken is a very bad decision. There is, in fact, no subject for discussion here. The only thing is, someone may want to take the easy way and ask for advice from those who have already solved this problem. Actually, I gave you this advice from the very beginning, without really understanding what exactly you want. People constantly want strange things, and when they want it, they also want it on New Year's morning and in a different language...
And yes, I really don't understand something in this world. I'm saying that the author is smart. I'm saying he's prudent. I'm saying that he is able to predict the consequences of his actions. I'm saying he created a great game. I admit that I respect his (and not only his, however) right to self-expression and to have his own opinion. And after all this, it turns out that I sound hostile towards the author? :)