I remember when I was still in secondary school, I saved up for my own PCI based network interface card for my computer so I could join my friends when they did LAN gaming. The very first game I managed to play was Delta Force 1, and boy it didn't disappoint.
I remember my one friend and I spent countless hours on the Ice Floes map with us noob tubing and sniping each other till the early hours of the morning. When also co-op'd the missions, which was good fun. I wouldn't mind checking out DFX extreme either as it's one of the DF titles that I didn't manage to play back in the day