There are certainly things that Cleve recognized as a problem as far back as the original "beta" that was released 20 years ago, that Cleve promised he would fix shortly, which were never fixed in the much later released demos, and are still not fixed now. The biggest example is the food bars, which don't do anything, and haven't done anything for 20 years. Cleve always said that he would get rid of them soon, or even that they were already gone in the current version, but somehow they are still there 20 years later. In that respect it really is like he hasn't done any work on the game.
But then, when it comes to fleshing out content, he clearly has done work, and it sounds like plenty of it. I haven't played the game, but it sounds like the game world is much more fleshed out then the early beta, and although I haven't heard much talk about them, it does sound like the areas beyond the first town are in the game and at least somewhat fleshed out.
It's almost like he can world build with his engine without trouble, but has a really hard time actually changing anything within the engine itself.