Rook disappeared in a daily game

My opponents rook has dissapeared very early on in the game. Any ideas what happened or how to get it back?

It sounds like your opponent's rook might have been captured or trapped early in the game. Here are a few possibilities:

Captured: The rook could have been taken by one of your pieces. Check the move history to see if this happened.
Trapped: Sometimes, a rook can get trapped by pawns or other pieces, making it unable to move. This can effectively remove it from play without it being captured

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Misplaced: In online games, there can sometimes be glitches or errors that cause pieces to disappear. If you're playing online, try refreshing the page or checking the game log

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To get the rook back, if it was captured or trapped, there's not much you can do within the rules of chess. However, if it's a technical issue, contacting the support team of the platform you're playing on might help resolve the problem.

Have you checked the move history to see if the rook was captured or trapped?

If it is the game you are playing now, it's looking like you're opponent chose to start the game with rook odds.