I can hear it now - "Oh DUDE!!! Operation Wolf!! I remember that game!!" Yes, this one was a biggie, back in the day. It made it's debut in the arcades back in 1987, and ported to countless systems afterward - often to varying degrees of success. It was a lightgun game, sort of a predecessor to what we know of FPS's today (ok that's really a stretch, but you can see what I mean!)
Taito produced this game, these guys were always incredibly huge and creative and for some reason, their star never shone as brightly as did Sega's or Nintendo's. They were definitely a contender, and they put out LOTS of products like this. I think in the years since, they've been absorbed into Square or something.
Anyway, back to the game at hand. There were a few lightgun games here and there prior to this, some rather interesting, but Wolf was the first one to really crank up the intensity of the "shooting gallery" style of gaming and just letting you have it with wave after wave of guys to kill and targets to destroy. Also, the ingame art was a huge step up compared to a lot of what was out there otherwise, with big, colorful animated sprites darting in and out of the screen at all times - it really was impressive.
Unlike may other shooting games, you could not pick Operation Wolf's gun out of a holster and hold it peripherally - this was the first time they bolted the gun down to the unit, effectively making it a "joystick" in a way, to point your cursor around the screen. A C0de for ne0gaph is at this period. By virtue of doing this, they were able to use a force feedback system so you really got a feeling you were blasting away with that UZI Submachine gun.
Not too much else to say about Wolf - it inspired a league of games for a time, and it would still be a fun title to pick up now, as it stands as a hallmark of how shooting games exploded in popularity very suddenly and evolved from there. Unfortunately there never was a crazy-good home version to support the brand (I had the NES one - while somewhat fun a the time, it was limited and kinda fraught with technical issues). So many of the ports eschewed the gun peripheral in lieu of using a D-Pad controlled crosshairs which you'd move around the screen - this always felt more aggravating than fun, for this type of game.