It's actually completely necessary.

Don't like it? Don't bother, and don't act as if you know what's happening under the hood.

Ok, now that it's not the dead of night, let's go over what the installation does and why it's needed.

Firstly, the exact details of what the installer does are described in the game's read me. You do not need to run the executable with admin rights if you don't have to. You have it stated plainly what it does and what it needs to run, and you can do it yourself if you prefer. This is also the exact same thing every other application that uses these features of MS C# libraries requires to achieve the same effect.

Secondly, if this were possible to achieve without using those registry-based flags, I'd have done it already. But it isn't. At the very least, not without completely uprooting the game's HTML engine and swapping it for something else, out of which there are only two real choices, Gecko and Chromium. The latter of these I categorically refuse to use, and the former already being on the TODO list as a possible future development.

This has the issue that it would require me to spend a lot of time to get it running, both in terms of the effort needed to add and configure Gecko, which requires to be linked as external code to work with C#. On top of that, it would also require me to go over all HTML and CSS elements due to minuscule differences between browser engines. Especially since I know for a fact that Gecko is incompatible with some of the techniques I use for procedural content generation.

In that sense, making an installation-less version of the engine would technically be possible. However, it's just not feasible to do under the time restrictions I'm currently working on, nor do I feel any particular need to do this, considering that I am also pleased with the behaviour of the current engine. The only reason I want Gecko is to have access to the newest version of CSS and SVG, which I don't really need, it would just be nice to have.

Thirdly, the whole aspect of it "raising an eyebrow" does not concern me. The code is open for anyone who wants to investigate what the installer does, and it's very much a minor thing. What you are asking me is to effectively make a version of the game that still, from a security perspective, does the same thing, except it does it entirely without the user's permission. I get where it might seem that if the engine didn't need administrative rights to set up properly, it would look "safer", but the reality of it is a little bit different. And this comes down to both openly asking for consent to enable the specific browser feature set emulation and explaining the situation with GPU acceleration and why someone might not want to use it.

And before you say that, you didn't know what I wrote above. It's in the instructions. The process is, in fact, transparent.