It was SNK, I was a huge fan of it at my local Dave and Busters. Never beat the last boss, tho - he had some "trick" which wasn't translated correctly in the Engrish and thus the game was mostly impossible.
There was a 3D sequel too (Second Nightmare) that ran on the Hyper NeoGeo 64 board. SNK also developed an overhead action NGPC spinoff called Dark Arms.