New Chess Variant Inspired by UltraBullet

I am actually proposing TWO VARIANTS here. They are both the same until the words FIRST VARIANT and SECOND VARIANT appear below.

Possible names for this new variant include: Illegal Move Chess, Premove Chess, Prediction Chess, Forecast Chess, Bluff Chess, Bluffing Chess, Blind Chess, Slow Motion UltraBullet, and Slow UltraBullet.

In regular chess the game can end by checkmate, stalemate, draw by repetition, draw due to insufficient material, resignation, or draw offer accepted.

In regular timed chess, the game can also end if a player runs out of time on their clock.

In this new variant, the game can also end if a player makes X number of illegal moves.

Why might a player make X illegal moves?

As UltraBullet players know, players often make illegal moves accidentally when premoving because they submitted their move before knowing their opponent's last move.

UltraBullet players make premoves in order to avoid losing on time.

In this new variant, players will submit moves before knowing their opponent's moves as well. But they won't do this (necessarily) because of time pressure.

Rather, players will submit moves before knowing their opponent's moves because their opponent's moves will not appear on the board until... (FIRST VARIANT) ...an illegal move has been played or (SECOND VARIANT) ...they submit their next move (as when premoving).

Make sense?

I think the variants would be fun to try out with values of X ranging from 1 to 20ish.

The game can be played on any time control.

Thoughts?

Once I get confirmation that the two variations are coherent and understood by others in the same way, I'll create a poll to get the crowd's consensus on the best name for them. Then once there are agreed upon names, I'd like to popularize the variants and see if we can get support for Lichess to develop them and add them to the site.

Wow! It's (they're) very...different. I, for one would support these variants, and I believe I understand every aspect. One question, what happens when a king is captured?

Kings do not get captured.

If checkmate happens, the game ends (and the current board position is revealed).

If a check happens that is not checkmate and the player does not respond to it by for example moving their king out of the way of check, then that is an illegal move. When the illegal move is played, the current board position appears and the player whose king was checked is given the option to submit a new move (now with full knowledge of the board position) and so will hopefully submit a legal move to get their king out of check.

I also thought about this idea (the second variant). It's something like 0+0, but with time dilation.

Yes. Playing the second variant with a longer time control such that one could think up higher quality moves would improve one's intuition for time scrambles in UltraBullet when it's effectively 0+0. I really want to try it out.

I found the website Dark Chess dark-chess.com/ which is an awesome variant with imperfect information, as well as Brain King brainking.com/ which has many more awesome chess variants. Unfortunately players don't seem to be on the site anymore.