The game idea looks nice, it seems like you've hit on a universal truth about games. That is the best ones have a super minimal gameplay loop that can be expressed with very little in terms of mechanics and assets. Once you have that loop, you can stretch it, build other loops over it, dress it up with an interesting aesthetic, but whether or not the game is fun will ultimately depend on having a nice, tight loop.
I enjoyed your discussion of handmade philosophy. As someone who has been building games mostly by scratch on and off for a couple decades, the handmade thing just "makes sense" to me, to the point where it can be difficult to describe why to someone coming at it from the other angle. I've tried really hard to empathize and understand not only where they are coming from, but also all the history and cultural context behind it.
I think there's a couple interesting tidbits. A lot of the common opinion, even among hobbyists and indies seems to be shipped out of big AAA shops. It can be very perilous to do your own engine at that scale, the tradeoff is a more unique expression of your game idea, at the cost of developing an incredibly complex system from the ground up. Any "greenfield" project like this has its risks. You bring up a really good point, that if you aren't trying to build a general-purpose engine, it's not as complex of a task, but to create a game of sufficient complexity as to compete with the other AAA offerings, you're going to have to pull off a lot of the same bits.
Scaling down to indie developers, it's a question of where to spend extremely limited resources (time, energy, money). I've seen some really inspiring indie games that used unity, and by freeing themselves from writing game code, were thus able to spend a lot of time writing and refining their narrative structure. The gameplay itself might not have felt as novel, but they exchanged that for a really neat story. Assuming they even had the skills to write gamecode, the only way they could have done the same game handmade would've been to significantly increase dev time.
The last thing I think about, is that there are two very different personas who masquerade under the same guise: tinkerers and makers. The former, the tinkerer, might be perfectly content messing around with engine ideas or code structures and never actually shipping anything. This kind of person might give the impression that by doing things by scratch, you are stuck in a purgatory of incomplete projects. It's not true, they just have a different goal than the maker. A maker has an end goal in mind (a shipped game) and is using the handmade "engine" as means to that end. There's nothing wrong with either persona or objective, but someone could easily look at the graveyard of incomplete engines as damning evidence that handmade = never finished.
All those words to say, there isn't a one-size fits all solution. The objective of a handmade community isn't to convert every single person possible over to the "better way" (for some projects, unreal or unity might be the better way), rather it should be about legitimizing it as an option (which I think your video did a fantastic job of outlining), and then for those who choose that option, the community should be there to help enable, encourage, and support their journey.
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One last addendum, when you talk about a tool that is only for one person or a small group, I generally point to a jig. A woodworker might have the same general purpose tablesaw as everyone else, but it's also almost always a guarantee they've got a bunch of jigs spread across their workshop to tackle the specific challenges of their projects.