ARMA: Cold War Assault has a few weird issues, most of which are caused by the developers, not GOG's faults:
a) The GOG version has not the latest official patch applied and it's hard to find it anywhere else on the web because even the official post in the BIS forums links to lots of expired download links (may have changed by now but was definitely the case a few months ago - I haven't received an update message since then, however, so I'm positive the GOG version still doesn't include the patch).
b) the original Cold War Crisis / 1985 campaign should be played with the base game's executable (patched up to 1.45 or something, beyond that it's the Resistance executable) which is missing from Cold War Assault. It was still present in the Game of the Year edition of Operation Flashpoint, though. When playing with the Resistance exectuable (the only one left in ARMA: CWA) you will run into these issues:
Major problem: the AI has been rewritten for Resistance and doesn't work properly in the original campaign. For one the AI navigation has been somewhat rewritten and is a little unreliable in the original campaign, at times it may not enter crucial triggers. More importantly: The sight range of the AI is in Resistance so large that units which should not see each other (or the player) actually attack, massively ruining the balance in some missions, especially noticeable in case of tanks (the last tank mission is basically unbeatable without cheating because you have to fight dozens of tanks at once, most of which should be out of range).
Minor problems: Resistance added a few features which were specifically designed for the Resistance campaign, the 1985 campaign was not adjusted to those. This includes the ability to use sidearms (on the equipment screens you can see the sidearm slots but you are never able to fill those in the 1985 campaign) as well as the ability to store equipment in vehicles. These features won't hurt the campaign but weren't meant to be present there.
So the game really should include the original OFP executable.
c) On the Nogova map there's a few texture issues which were not present in either OFP version. Buildings which can be entered have textures for static ones. This means you can enter the buildings through closed doors, you can operate invisible doors, climb invisible ladders, you appear to be floating, you can see the surroundings when inside the building. The model data seems to be correct, the textures not.
Technically BIS is probably to blame for all these issues *but* considering that OFP was already available on GOG I'd kinda make an exception in this case because a superior version of what is technically the same game exists and was even present on GOG in the past.
Post edited September 10, 2013 by F4LL0UT