If there was a shoot-em-up in an arcade, I'd play it [there weren't many, everyone was busy with Tekken and Time Crisis and Daytona cabs, not enough floorspace for a plain-old shooter].
I didn't play much else in terms of shmups, until years later, when I picked up MAME [as part of my "emulate everything" campaign, where I'd just try to get a bunch of random emulators working, even if I had no use for them

And now almost all I play are shmups.