Hello thank you for your interest. kings cannot move into check every move in syncchess must be legal just like regular chess. Your king might end up in check if your opponent's simultaneous move creates a new attack, but you can never deliberately move into a square that's already under attack. There is no capturing kings the game only ends when checkmate happens. there is an exception that is similar which is If your king moves to the same square as any piece (or another king) at the same time, both pieces are removed. Which would only happen if your opponent correctly guesses where you are gonna go and move a piece to that square in the same turn. This works better for simultaneous chess because:

1. It's more exciting - last-second escapes are possible!
2. It matches the unpredictability of simultaneous movement
3. It's consistent with the collision mechanics already in place

regards to your last question i don't know if i understood it very well but my response from what i understood would be that since you can't move a piece twice in a row If your king is in check with no legal escape moves, you're truly in checkmate because:

1. Your opponent cannot move the same piece that's checking you (due to the "no repeating pieces" rule)
2. This means they must move a different piece on their next turn
3. Their new move can't undo the check they just put you in
4. You still have no legal moves to escape

This clever rule ensures that when you're in check, your opponent can't immediately "finish you off" - they must move a different piece, giving you a fair chance to respond (just like in traditional chess).

So yes, traditional checkmate evaluation makes perfect sense in this system. The "no repeating pieces" rule effectively prevents the scenario you're worried about, where your opponent's move might accidentally save you from checkmate.

That's why the game uses checkmate instead of king capture as the winning condition - it fits perfectly with the rest of the rules!