Well, if any one encounters this problem again, I might have a sufficient solution. Id been dealing with the exactly same issue and I solved it temporarily with moving 'Addons' folder from 'arma 2' to 'arma 2 operation arrowhead' directory. And it really isnt the step in the right direction. (Steam will try to download the whole 8GB directory again). You might try the the directory junction (but most of the people just dont want to mess with that). The solution Im using right now is a bit more simple: As I understand it, the parameter "-mod=%_ARMA2PATH%;EXPANSION;ca;@dayz" more specificaly the %_ARMA2PATH% variable tells the game to add arma 2 path to its working directory. For some odd reason, my game does not know its value (yes, ive run arma 2 a few times, to no avail). So, instead of this variable/placeholder, just overwrite it with the full path to your arma 2 directory. For me, its: "D:\Steam\steamapps\common\arma 2 operation arrowhead\Expansion\beta\arma2oa.exe" "-beta=Expansion\beta;Expansion\beta\Expansion" "-mod=D:\Steam\steamapps\common\arma 2;EXPANSION;ca;@DayZ" -showScriptErrors -skipIntro -noFilePatching -world='empty' -nosplash -noPause (using beta obviously) The downside of this is the length of the entire string, so you wont be able to paste it to launch options in steam (so no steam overlay). You have to run it from a .bat file. Hope it helps.
