if it -is- the same one that was on Amiga Format... i've thought this for years!!
the aliens look more Giger-esque (only green as i recall) and therefore close to Alien Breed (2d) and of course in turn, the Aliens films... this imho can only be a good thing!
i remember thinking the demo rocked, and although i enjoyed the game, i never saw any aliens like that in the game itself.... something of a disapointment.
also, the red dog-alien things reminded me of the boars in ZX Speccy "Robin o` the Wood" ... but thats neither here nor there.