Just as a side note, and something to take into consideration.
Some people tend to use:
$($+(%,staticVarName,.,$identifier),2)
Other people just use:
%staticVarName. [ $+ [ $identifier ] ]
Personally, I prefer the brackets, because I like the seperation in code. (Atleast while using variables)
The other option is to use Hash Tables. (You have to save (/hsave) before you exit mIRC, and load (/hload) them after you start mIRC.) Hash Tables are extremely useful, and are often a lot cleaner for this sort of thing.
Example:
hadd -m HealthPoints $nick 100
$hget(HealthPoints,$nick) would return "100"
hinc HealthPoints $nick
Would increase that number by 1 (so it'd be 101 if you checked it).
Hash tables generally allow you to handle it a little more cleanly, for example you could have a table "Game1" and various stats stored for each nick.
var %table = Game1 , %health = $+(Health.,$nick) , %mana = $+(Mana.,$nick)
; User uses a potion to restore..
; health by a random value between 200 and 250
; mana by a random value between 100 and 125
hinc %table %health $r(200,250)
hinc %table %mana $r(100,125)
msg $chan $nick currently has $hget(%table,%health) health and $hget(%table,%mana) mana.