It still takes a lot of time. Prototype or not. And compared to the last updates, this one is way more moderate.
Last time we've left of with the addition of immediate things to do, which begged the question of what to do next. Exploration was a big part of the concept, springing from its replay-ability (from procedural content), which was not yet shown. So far a bit of combat, building, magic and some other stuff was in the game, but nothing that would break the one dimensional aspect of the scene: Where ever you looked, it was always a bunch of cubes.
To better show what the final product would feel like, it was time to introduce some structures that would spawn in at a distance from the base. One was the sudden idea of placing waterfalls, the other to place specters of dead dwarfs (who also were stuck in the mines). Hindsight, neither of those were simple to implement, yet doesn't sound too difficult (keeping up with the hack-n-slash approach to making this prototype).
Two weeks it took. Well, not two full weeks, as there were a lot of crashes of the build that needed to be hunted down (yikes), things tweaked (fixing code, adding new stuff), and refining/modifying and testing. Or adding last minute things like speech or music.
You've to keep in mind that some stuff just takes a hell lot of time to implement, even at this low level of execution. First, you need to be 100% sure how to make "the" thing, otherwise you'll spend most of your time learning and not completing said thing. Second, after making said thing, assets and all the plausible scenarios need to be "run" in order to make sure said thing is implemented correctly. Luckily, most of the stuff in the game is modular, so adding a new thing (that works with another) is relatively painless (unless you forgot something to add, which caused the game to crash, and thus only managed to solve it today!). All the while keeping everything in check, alive, healthy and creative.
The expansion (the two structures) might seem lackluster, however there were some additional circumstances that made the work that much more involved. Stuff like taking care for collision, handling clipping (which affects objects and particles differently), event handling, and so forth [the majority of the game runs solely on collisions, no tick in sight (mostly); which is somewhat of a silly but proud achievement of mine, if you can call this an achievement, because it needs a lot of planning and problem solving to circumvent certain outcomes or needs)]
There were moments that halted production for days, because the project has already reached a level of complexity that is difficult for me to trace back with ease (especially if you can't catch it in the editor, nor find out from a crash). Plus, as everything was made up on the spot, a lot of the background (of execution) just weren't there and had to be iterated on. It runs, and suppose that's what matters at the end of the day.
Would mention, on the side, that as more and more stuff is being added (especially with exploration), the more difficult and time consuming it has begun to "just" show off the interesting bits of the game (like not showing the map, or just some UI). So to remedy that, had to implement a basic "console" to give my character some cheats in order to be able to show end content. As how it stands right now, you cannot just die from the boss (really one tough), but die way before you get your first mob kill (like dying from drowning alone, or fall damage from rocks). Which means that in order to reach all the content in the game, you'd need to be playing for more than 10-15 minutes the very least, and be lucky as hell (with the gen); stuff can spawn behind you and snipe you at an instant. From a design perspective, it really shows how much "padding" is missing from the game (like upgrades, armor, better weapons, combat spells, etc.), albeit this is just a prototype and not the intent behind it all. But still, it adds another level of challenge for showing of your concept ("game") as a solo dev. But that's marketing stuff. So here's a short video of it all instead: