I don't believe Ultimate / Play The Game ever released ST versions of 'Knight Lore' or 'Alien 8', but were there ever fan ports or recreations of these games for the ST?
There were certainly very faithful PC recreations (with updated graphics) a few years ago - I still have them backed up somewhere. I can play the originals on my real Spectrum but the slowdown when there's a lot going on on the screen is irritating, especially when it affects the critical timing of your jumps / moves. I hate being killed by the game's technical limitations rather than by the game itself..
Along similar lines, (although not 3D isometric) has anyone ever thought of reproducing the Spectrum classic ATIC ATAC for the ST?
There was a PC port of that as well, but it actually improved the graphics a little bit more than necessary - the Spectrum version was a beautiful looking game in its own right, all it really needed was the colour clash removed. I never saw the Amstrad CPC version (if exists) but that was probably graphically quite close to the ideal.