This game isn’t so much “underrated” as it is “America doesn’t know what it missed”. The Firemen is one reason that I’m a heavy proponent of emulation: I would have missed it otherwise. Basically, you and an AI partner (who is competent, considering this is 1995) are trying to put out a massive fire in a corporate building. Of course, the fire is HUGE, and it basically plays like a SHMUP where you have limited ammo. It’s extremely fun.
I fully recommend the Hardcore Gaming 101 piece on the game as good reading. The Super Famicom version is far superior.