This would be equivalent to a joker or wild card in English. It is not only used in games though. Sometimes a word can be a comodÃn. I recently heard a Spanish podcaster who used comodÃn when talking about a word that is used to mean whatever you want it to mean.
It is also the word used when doing a computer search and you need a wild card character. Often that is the asterisk (*), wild card or comodÃn.