You decide to continue the pattern of threes and try code 999 next.

To your surprise, the DEAD MOUSE simply vanishes. You wave your hand in the space that it once occupied to see if it's invisible, but nope, it's just been DELETED out of existence. You guess it makes sense that if the very first code (000) sets things to their starting conditions, the very last code (999) ends them. You'll have to be careful not to use that power irresponsibly.