A highlighted review from the http://www.gtw64.co.uk archives
1986 Probe Software
Mantronix was due to appear on the C64, along with a release on the CPC, in 1986, sometime after it was first released by Probe Software on the ZX Spectrum. Like so many Spectrum games it failed to ever get released and today our only evidence of its existence is from an advert stating it was forthcoming on the other 8-bit systems.The premise of the game is that you are a bounty hunter, who has sent a robot to the excellently named planet Zybor to locate and bring to justice four criminals, who are in hiding and protected by defence humanoids. Playing the Spectrum version and you see the game is enjoyable enough and the music and sound effects are in the classic jolly 8-bit style, if that makes sense!
My first thought upon seeing the screenshots was that the reason it wasnt released on the C64 was its isometric, Knightlore-esque viewpoint. However, a quick trip to the Lemon64 forums soon provided me with a list of isometric games that appeared on the C64, including a direct port of Head Over Heels, that certainly plays well enough with the benefit of music and sounds provided by the all-conquering SID chip.
Technically however, it does seem the C64 does have some technical difficulty with the process required for a fast isometric game. The C64 using tile mapping, which provides faster performance overall but isnt well suited to the isometric style that flooded the Spectrum in the mid eighties and many gamers complain of the games being too slow to be enjoyable, Fairlight being a classic example. Is this the reason why the game was eventually pulled from a C64 release? If so why not release the CPC version, which had ported versions of games like Knightlore? Frankly a game running too slow never really stopped many companies, then or now, on the Spectrum games like Outrun and Wonderboy are notoriously slow as soon as the screen becomes even slightly complicated.
If the market for isometric games was flooded on the Spectrum by the mid-eighties, possibly the most logical conclusion is that the game quickly sunk in terms of sales, and Probe Software, who were prolific releasers of games on all 8-bit formats, may have moved on to other projects. They certainly released most of their games on the Spectrum, perhaps this was used as a testing ground, and if a game had enough success they would continue with the port to the less successful C64 (in the UK at least) and CPC.
Yet another missing game for the archive, and a CPC version may exist too. Will either version ever be found?