From the inlay (Vic 20 version):
HELL GATE is a hyper fast blast for the VIC with 8 or 16K RAM expansion. It has many unique features - such as simultaneous control of 4 laser cannon and automatic smart bombs - plus a seven-place Hi-score table and full Attract mode. A fast, colourful and smooth bit of Galactic mayhem for those who like zapping and goats.
From the inlay (C64 version):
HELL GATE on the 64 is certainly no REVENGE or HOVER BOVVER, being the VIC 20 code tweaked to run on this system. However we are offering it at a bargain price to those who like an unusual shoot-'em-up, fans of Gridrunner and Matrix should enjoy themselves and the game is challenging to all.
Hellgate is an unusual shooter as the player controls four turrets simultaneously. One of each is mounted on the four walls at the edge of the rectangular playfield. The turrets opposite each other move in tandem - moving the controller left moves the bottom turret left, and the top turret right, and vice versa. The left and right turrets are similarly controlled by moving the controller up and down. Pressing the fire button causes all four turrets to shoot simultaneously. Enemies spawn inside the playfield and must be destroyed by the turrets to move to the next level.