Alien Storm is a fondly remembered game and compilations like the Genesis collection on Steam and the Mega Collection on multiple consoles have helped keep it alive.
You have a choice of three heroes: a generic "Bro" character (think Axel from Streets of Rage), a brunette woman and a T-800 style cyborg. The game basically plays like Golden Axe, but with guns and aliens instead of swords and dragons.
The game to me feels highly influenced by the film and cartoon series Ghostbusters. If they redesigned the characters it could easily be a Ghostbusters game. Like most Sci-Fi themed games of the time (Contra, R-Type) it draws heavily from HR Giger's designs from Alien. This game also features the ugliest aliens I have seen in any game which are clearly influenced by John Carpenter's The Thing.
The game is solid, but it never quite reaches the heights of Golden Axe, which is a joy to play even today. I think Altered Beast is slightly more fun to play as well if just for the transformation gimmick. This game has some first person sections which must have been an inspiration for Sega's later Arcade game Alien: The Gun. Alien Storm has the typical Sega polish of: digitized speech "bad breath, dude", colourful graphics and outlandish humour. Do check this out especially as it is available on so many platforms.