Game runs in Fullscreen or Windowed.
Can't find an option or .ini file to edit to get game to run in chosen windowed resolution?
Are there Startup commands ect to run at chosen resolution ect?

**Edit

All good figured it out :)

Really easy one.
Feel pretty dumb not checking this before posting this thread to be honest but to complete my shame here it is:

Uncheck Fullscreen box in options so game opens in a window.
Then simply grab the corner of the window with your cursor and drag to enlarge the window :)

Thanks a bucnh :) never thought of that myself either