Gorf is an early arcade shooter that feels like a poor relative to many of its peers of the time.
It borrows most of its features from other games (one wave is actually called “Galaxians” although I do believe that the developers properly licensed it from Namco) and doesn’t bring anything new to the table in terms of gameplay, but it did pioneer one thing. And that is: in the use of synthesised speech. Gorf was one of the earliest video games to use it (and although clear, it is quite robotic).
As a shooter, Gorf is a challenging, five stage, fixed-screen, mission-based blaster (a VERY vertically squished screen at that, which is what the game was like – it’s not an aspect ratio problem).
The missions are as follows: 1. Astro Battles (Space Invaders clone), 2. Laser Attack (a somewhat original dive bomb attack wave by ten enemies, two of which can fire continuous lasers), 3. Galaxians (clone of Galaxian), 4. Space Warp (shoot enemies while flying down a wormhole), and 5. Flag Ship (shoot through a force field, then shoot the mother ship core – an early boss battle!).
Gorf was developed by Dave Nutting Associates for Midway and was released in 1981.
More: Gorf on Wikipedia