Mission Genocide

Mission Genocide

Developer	Paul Shirley a.k.a. Rotovision
Company	Firebird
Publisher	Firebird
Musician	Unknown
Release	1987
Platform(s)	CPC, Commodore 64
Genre	Shoot'Em Up
OS
Game Modes	Unknown
Controls
Media
Language
Information	Unknown

Mission Genocide, originally titled ZTB (for Zap the Bastards and later Badstars [1]) and still named thusly on the loading screen and elsewhere, is a game by Paul Shirley (a.k.a. Rotovision) for the old generation of CPCs, released on both tape and disc and compatible with all models.

The game is mentioned fairly often for its smooth and pixel-perfect vertical scrolling, which is done in hardware using the CRTC. It is also notable in using a very fast method of plotting sprites, which takes advantage of the 16 colours of graphical Mode 0 by using 3 for sprites, Ink 0 for transparency, and the remaining 12 as 3 duplicate sets of 4 colours for the background: the roles of these Inks are arranged according to binary logic so that sprites can be ORd onto the background and ANDed to remove them, a method that is much faster and more memory-efficient than storing a sprite and a masking table and then performing all the relevant masking operations between these and the background. The name Rotovision has been used to refer to either of these techniques, but this seems actually to be an alias of the game’s programmer Paul Shirley: different ROMs of the game display one of these two names.

Shirley later ported Mission Genocide from the CPC to the Commodore 64, although he says that version is “not worth the tape it's saved on”, unlike the “technically impressive” original version.