Oldest set of rules would be Tractics rules for WW2-modern (for the time) wargaming, used for micro-armor but could be used for other scales. Still have my old Angriff (for micro-armor) rules, too. Both came out in early 70s, I think Angriff was dated '71, and Tractics around '71 or '72. Tractics came from Gary Gygax and was co-authored by him at about the same time he did the original D&D rules in the little brown box. I still had that set as well but I dont know if my son took it with him or not when he left for the Navy. Havent seen them around since then. Next after those would be Ship o' The Line, the Battleline rules for age of sail gaming that Avalon Hill used as a basis for Wooden Ships and Iron Men, written by the same author. In '78, Superior Miniatures came out with their line of space ships and armored vehicles, which I picked up late that year or early the next - the starship series was called Starfleet Wars, and the armor game was MAATAC. Both are now on the market again but with new rules for the spaceships under the name Galactic Knights.
I have the second edition Blood Bowl, always loved the 'astro-granit' field instead of the later cardboard surface, but that is a relatively recent addition at under 10 years ago. Before that was the first or second edition GW Space Marines/Epic with the Titan Legions set as well. Think that was about 93 when I managed to get to Cold Wars in PA.
Gads, being an old fart can meen having older games just because I was around way back then!
