I mostly made this variant bc I wanted to make something like chess960, where opening strategy applies, but the varied starting conditions lead to memorized openings not working, and a variant with some stronger pieces to cause both chaos and tactical thought.
My Custom Variant: Upgrade Chess

At first glance, this intrigues me. I’d have to think about / analyze it more, but it sounds interesting.

lets think about points here.
pawns > 0 points, but more like 4 since Sergeant is like 1.5 points
knight > +4 points
bishops > +8 points
rook > +8 points
queen > +5 points, king becomes harder to kill
king > > +5 points, king become much harder to kill
basically you would never upgrade pawns or knight, and it is better to upgrade king than queen since your king becomes safer.

I’m wondering if it would be better to make it so that you can’t upgrade your king. That would help some of the issues involved.

@Green_Sleeves Yeah, I've been thinking it over and that's the best idea. I'll change the original post so that king no longer gets upgraded.

Although I do feel this makes upgrading the queen a bad decision, as it's now just +3. Maybe instead of upgrading the queen, you can upgrade both royals, making the queen into an amazon and the king into a royal general.

Possibly. Basically, here’s what I’m thinking. Upgrading the queen to an Amazon would be a matter of weighing whether you want more material total, or a single overpowered piece. Personally, I think that’s a cool strategic decision to give people. But having an upgraded royal sounds like it has its own issues.

lets think about points here.
pawns > 0 points, but more like 4 since Sergeant is like 1.5 points
knight > +4 points
...
basically you would never upgrade pawns or knight, and it is better to upgrade king than queen since your king becomes safer.
I would say that upgrading knights might be slightly stronger than +4, as it increases their mobility, control, and "potential control" drastically. What I mean by potential control is the squares that a piece can get to in 2 steps. The more potential control you have, the more mobile you are, the easier it is to threaten the king, and you can control the same square while still moving. The knight isn't able to control the same square and move, but the Wildebeest can. I would say upgrading the knight is a solid option.
As for pawns, a sergeant controls more squares, and when the primary purpose of a pawn in the opening is to control the center, they achieve this goal easily. They also can form strange vertical chains or mixes of vertical and diagonal, along with standard diagonal chains. A single pawn becoming a sergeant isn't worth much, but doing that to all your pawns is worth more than the sum of its parts. It's similar to a bishop pair; they increase each other's power.

So each player has a limited quantity of upgrade points, spends them to upgrade choosen pieces - and then the game begins...

Kind of. The default is only upgrading one type, although you can upgrade multiple if you and your opponent agree on doing so.

1 upgrade makes it regular chess but similar. Changing the amount makes no sense
Since the best people won't make multiple variants (one with 1,5,...)
Basically, before the game starts, you can pick one kind of your pieces (except the king) or your pawns, and upgrade all of that kind of piece. You do not know what your opponent upgraded until the game starts, and you are not able to change your choice as soon as it starts. Here's a list of what pieces become:
Pawn -> Sergeant
Knight -> Wildebeest
Bishop -> Archbishop
Rook -> Chancellor
Queen -> Amazon
Is this a good variant? What changes should I make? Is it balanced? I don't really have much more to say, I'm just throwing this idea out into the void.