Ok lets say the words "<nick> has joined the game" appea.
How would i do it so if the nick is on a file for it to msg chan saying like User is on join.txt or w/e

what does a user do to join?
What do you expect to have posted besides the user has joined the game?
what do you think will be in the text file, and hows does that relate to someone joining the game?

Ok sorry for that poor description...

When ever my servers bot says:
"<nick> has joined the game"
and on <nick> is a differnt nick

I was it to read join.txt and if the nick on
"<nick> has joined the game"
is on the text it would message the channel with "user is on list"

That's still pretty vague, but I think this is what you're asking for. I don't know how your code is structured, so I leave it to you to integrate the following:

...
window -h @joins
loadbuf @joins join.txt
if ($fline(@joins,$nick,1,1)) msg $chan user is on list
window -c @joins
...