Druid (Commodore 64, Amstrad CPC, ZX Spectrum - 1986)
Cover art (Source: credited in the manual)
Druid II: Enlightenment (Commodore 64 - 1987, Amiga, Amstrad CPC, ZX Spectrum - 1988)
Cover art (Source: credited in the manual)
Iron Hand (Commodore 64 - 1989 - unreleased)
Cover art (Source: confirmed by the artist to Games that weren't)
Mutant League Football / ミュータントリーグ・ フットボール (Mega Drive - 1993)
Cover art for the European version (Source: confirmed by email by the artist, via OVGA)
Mutant League Hockey (Mega Drive - 1994)
Cover art for the European version (Source: confirmed by email by the artist, via OVGA)
Rebel Planet (ZX Spectrum, Commodore 64, Amstrad CPC - 1986)
Cover art (Source: mentioend by the artist on Twitter)
Soldier of Light (Amiga, Atari ST, Commodore 64, ZX Spectrum - 1988, Amstrad CPC, MSX - 1989)
Cover art (Source: mentioend by the artist on Twitter)
.Note: originally created for the book "The Stainless Steel Rat
Druid
Druid II: Enlightenment
Mutant League Football
Mutant League Hockey
Iron Hand
Rebel Planet
Soldier of Light