BEAST BUSTERS / SNK / Arcade
Beast Busters was basically SNK saying to Data East: "I'll see your Operation Wolf and raise it two more Uzis." The oversized console sported three submachine guns, and instead of taking you into the killing fields of Vietnam you're plunged once again into the world of survival horror.
This was actually the last game SNK released before they shifted all their game development to their own Neo Geo hybrid home console/arcade platform. I strongly suspect that, aside from just trying to differentiate from the other light gun shooters, the zombie setting was a gambit aimed at arcade owners who wanted one of these hot new machine gun games but were uncomfortable with Operation Wolf's living human enemies and potentially PTSD-triggering setting.
The setup is that there's this "off limits" city that's all walled off and barricaded, anyone who goes in never comes back out. Our players decide to wander in with submachine guns and "solve the mystery." You can choose which of the three you want from each position, I usually take Paul Patriot just because he looks the most prepared for this by far. I picture these three guys as like Dale Gribbel wannabe mercenary types though, a premise hilariously lampshaded when the second level starts and the heroes are basically like "Holy shit, we're in way over our heads, bail dude!" The heroes really do appear to spend the rest of the game just trying to beat feet out of the city, but somehow they keep working their way in deeper until they eventually wind up at the factory that appears to be the source of all these T-virus shenanigans.
So it's really like an early version of House of the Dead, but it's more concerned with just non-stop over-the-top goofy insanity rather than trying to scare you or be atmospheric. Most of your enemies are highly mobile zombies packing all manner of firearms, but that's the least crazy of what you face by far. Some examples? Two of my personal favorites are the bats toting .44 Magnum hand cannons and the giant eagles that fly zombie football players in so they can chuck Molotov cocktails at you, just to give you an idea.
With the actual arcade cabinet, this looks like it would actually be pretty fun for a crazy multiplayer game. There's some advanced stuff for 1989 like environments with lots of destructible elements, and some of the later bosses have insane designs, like a living combat jeep and Granfaloon from Castlevania. Unfortunately, it just isn't any fun at all with a gamepad - way too imprecise, and MAME also has issues with the fire button suddenly not working for some reason (the reason why it gets an NR score). There were apparently a couple of home computer ports of it, however, so you might check those out for better gameplay.