The Commodore 64 conversion of Nightshade was coded by Shahid Ahmad and published by Firebird in 1986. It is a reasonable, if slower, version of the original game from Ultimate. What is more interesting, though, is the enhanced version, released by Nostalgia in 2016.
The original C64 conversion of Nightshade is relatively close to the Spectrum version, except that it has completely monochrome graphics in the scrolling isometric environments (whereas the Spectrum version has some colour). It still has very simple gameplay (collect the special weapons and destroy four boss monsters, while surviving an onslaught from all the lesser monsters).
The enhanced C64 version has extra colour in the backgrounds (with added colour clash), new musical ditties, a new loading screen, saving high scores to disk, and the usual trainers. What it doesn’t have, unfortunately, is a boost in speed. The C64 version is achingly slow, whichever version you’re playing, although it is still playable.
The screenshots here show both versions. The enhanced version first, then the original monochrome version. Nightshade is not Ultimate‘s finest hour, but it’s not a terrible game either. If I was going to play it for fun, though, I’d probably choose the original Spectrum version, or the Amstrad, BBC Micro, or MSX versions, all of which play faster.
Final note: Shahid Ahmad, the programmer of the C64 conversion, has posted some interesting Nightshade documents (sent to him by Chris Stamper at Ultimate) on his blog. Click here to read them (part one; part two; part three).