Got plenty of old floppies for the PC (3.5", I'm not going to go completely off the rails on you about "back in my day"), most of those are warez from a family acquaintance who knew how to use .zip compression. Oldest legit copy from those days is the unexpected sequel, Battle Chess II: Chinese Chess, circa Interplay 1990. Now, being a twitchy little freak as most children are, learning the rules of a board game like xiangqi didn't seem as appealing as the demo levels of Commander Keen, so those were shelved pretty quick.
A few years back, got a boatload of old NES games from the untimely passing of an uncle. Several games I remember handing off to him when the thrill wore off for me. So, yeah, glad to have them back, still need to take the system to a nearby mom and pop game store specializing in console repairs to get some issues sorted out there. Lemme check on what's oldest from in there.
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Tie between Metroid and Tetris, since I don't feel like looking up which came out X months before the other. So, 1987. There.