Anyone who wants to try this scenario should avoid the "spoiler"s in my posts.
I decided to keep going...
I think this scenario would be better if:
1. There were no other iron/copper/coal/stone resources except the "infinite" ones.
2. There were biters, and they were a real threat. (Or there were some other time pressure such as a time limit or something - maybe some intermediate reward that gets less valuable as time progresses so it's not all or nothing but still provides good motivation. That might be better than biters because the secondary thing that was "good different" about this scenario was not having to care about pollution, good simply because it results in different-than-normal gameplay.)
The main thing that is actually different (in an interesting rather than annoying way) about this scenario than many of the other maps I have played is the "infinite" (yet spatially compact) resources, and that difference is resulting in some different gameplay. One of the things I wish Factorio did a lot more of is reward the player for good builds - that is, be more efficient/productive if the build is good. Normally your reward for making a good build is... it looks good, or "the satisfaction of a job well done" or whatever - what it fails to do (for the most part) is reward you with more stuff. This scenario, on the other hand, manages to pull that off to some degree. But in order for that reward to be meaningful, the extra stuff (per unit time) has to actually matter, and with no biters expanding/evolving nor any other time pressure, it really doesn't. Also, having all of the other "normal" resources just takes away from that mechanic of rewarding the player for doing well with the "infinite" ones -- any dummy can spend the time to chop the trees (or shotgun them, or ram them with a vehicle, etc.) and get those other resources, and there's enough of them on the map that they trivialize the "infinite" ones which should be the focus of this scenario.
Also, in terms of not wasting the player's time, I think this scenario would be better if:
3. The trees (and other items - you know what I'm talking about) were not densely plastered all over.
4. The player character didn't start with an empty inventory.
Now I think with the trees what you were trying to do is force the player to work with a smaller space (at least initially). That's a fine idea, but doing it with trees (which can just be chopped down) doesn't provide a gameplay challenge but rather an annoyance one - it rewards the player who engages in boring gameplay by giving them more space. Now if it were possible to have something (trees or whatever else) which were not destructible/removable by the player except by reaching some given goal, that would work well gamplay-wise -- but note that having some time pressure is once again very important otherwise the player can just "build small" to fit (or hand-craft, or time-multiplex a single factory, etc.), ignoring throughput, and again the result is boring (time-eating) gameplay.
The empty inventory at the beginning of the game was more of the same - it adds no interesting gameplay challenge, just more tedium for the player. (I had hoped that you had hidden some starting stuff somewhere, like in the trunk/boot of a certain vehicle - that would have at least rewarded someone for being on-the-ball, but alas the "solution" there was just painful hand-mining. Maybe there's a chest of stuff somewhere, but if so it would seem to be too well hidden.)
I would make more suggestions on how to take the scenario even further, but I'm not sure how to do it. What I have in mind is that it gets boring doing the same things over and over again essentially the same way from one play to the next. "Oh, it's time for blue science again?
". It would be nice if there were some way to make it so the player is spending their time more on what is unique about the scenario and less time doing the same old thing. For this particular scenario, maybe some intermediate rewards for meeting goals would be giving access to some prefabbed stuff? (Maybe just partially prefabbed so it presents a sort of "side quest" of figuring out how to finish it? Maybe having some of it unmovable/indestructible so the player has to work with it as it stands or not use it at all? That's starting to look like a whole other gameplay focus though.)
Anyways, my construction robots are now busy:
My 8 steel furnaces are hopelessly behind (there's a rather large backlog of iron ore, in large part because I was mining some of the "normal" resources just to get them out of the way), so the first use of the new space will likely be a new smelting setup (and a larger automated buffering system).