ok thats actually cool
Promotion to a different color variant

Sounds like a cool concept; promotion to walls currently exists, so a variant based off of smothered mate is technically already possible.
Firstly, this could also be a way to prevent stalemate; promoting to another side’s pieces so that they have something to move.
Secondly, I think that Teams 4 Player Chess with this would also be a fun idea, allowing for expanded strategy.

@spacebar, yes I think Any Color Promotion would be a good name.
Maybe there could be two submodes, one in which you can promote to dead pieces, and one in which you can't, and for teams a mode in which you must promote to a color of your team and one in which you can promote to an enemy color.

I think it could just be another option next to N-check and promotion rank. If you select "Any Color Promotion" there would be some boxes and you could tick which colors you can promote to.

finally someone with actually good ideas
I think there are a lot of new game rules that we should consider adding which would make this dead game at least a little more alive? (from the perspective of 4p variants, not standard)
Idea 1: Promo to different colors (as stated in this forum)
Idea 2: Promo on different ranks (if you promote on a closer rank, you only have options that are less valued than if you had promoted on the farther rank)
Idea 3: Ability to choose custom KoTH squares (self-explanatory)

Honestly though I think if we add too many rules 4pc turns from a little more complicated chess game to a full-on video game lol

I love those ideas, it allows more so much more creativity. Making simple video-games in chess would be awesome!

finally someone with actually good ideas
I think there are a lot of new game rules that we should consider adding which would make this dead game at least a little more alive? (from the perspective of 4p variants, not standard)
Idea 1: Promo to different colors (as stated in this forum)
Idea 2: Promo on different ranks (if you promote on a closer rank, you only have options that are less valued than if you had promoted on the farther rank)
Idea 3: Ability to choose custom KoTH squares (self-explanatory)
I suggested #2 here. All of these seem to me to be fairly simple yet potentially very strategically interesting.

finally someone with actually good ideas
I think there are a lot of new game rules that we should consider adding which would make this dead game at least a little more alive? (from the perspective of 4p variants, not standard)
Idea 1: Promo to different colors (as stated in this forum)
Idea 2: Promo on different ranks (if you promote on a closer rank, you only have options that are less valued than if you had promoted on the farther rank)
Idea 3: Ability to choose custom KoTH squares (self-explanatory)
I suggested #2 here. All of these seem to me to be fairly simple yet potentially very strategically interesting.
I think #2 is one of those ideas we all had at some point; you were just the first (or one of the first) to post it for people to see and discuss.
I heard that at one time it the written rules of chess did not explicitly state that a pawn had to promote to a piece of the same color, and so someone came up with this puzzle
In which an offbeat interpretation of the rules at the time would have implied that white had a mate in 1 by promotion to a black knight.
I was thinking based on this a variant that could be added would be one, in which, it would be possible to promote a pawn to a piece of any color.