Oh hmm I definitely entered it as \t, since I copied and pasted my script, but I added the backslash in.
The closing bracket character is escaped, and the only one that needs to be (since $ for example cannot mean the end of a string in a character class.)
Also, not all non-alphanumeric characters should be encoded (even if that is an idea) since only these characters and alpha-num form a valid URI according to internet standards. Even more so, the characters -_.~ should not be encoded.
I explained in the intro that this script will count down AND FROM a date.
The amount of CPU used by the timer seems minimal, the CPU usage of mIRC for me is usually under 1% using the script or not. The only point of the switch is so that the countdown does not go out of sync from what it should be, otherwise you could be seconds to minutes out.
In regards to the $read, just use a wildcard search - $read(hangman.txt,w,$2) (will match exactly that word as the line)
Quite a few /if\'s can be removed by using &\'s in the matchtext for on TEXTs such as the first one which could be !hangman & &
There is no need for (( )) for the conditionals of the /if\'s (can use 1 or 0 () in some cases)