Some missions were near impossible to win. But when, after that, I once decided to play the original campaign again, it suddenly felt like it's become considerably harder than it was the first time around. Later, I played the add-ons, made my own missions, engaged in multiplayer, and so on. I finished the original campaign when the game came out. I'm probably going to go back and replay them soon, but there's something peculiar I remember about its patches and difficulty.
I don't own the ArmA re-issue (might still get it one day), but I own the original boxed Operation Flashpoint and both the add-ons. This post contains light spoilers about the original campaign.
