Good things come in small packages. Here's a small download with a lot of gameplay and, even better, you can play it as either an SP or an MP coop mission! All this comes to you courtesy of one of the earliest OFP mission makers, Reddeth. This mission dates back to early July 2001, shortly after OFP's original release. No addons needed.
It's simple. NATO wants you to rid Le Moule of any pro-Soviet resistance fighters. This should be child's play, especially since the nearest supporting Russian forces are way up in the northeast somewhere. Of course, intel has made bad assessments before but they can't always be wrong, can they?
I played this as an SP mission. If I'd have the time to play this as an MP coop mission with a full team of gamers, I think I would have enjoyed it even more. Try it either way and decide for yourself.