There's nothing wrong with calling a game Realm of Impossibility, providing it's within the realms of playability. This isn't.
This is a maze game of sorts; the usual with lots of nasties that make directly for you and sap your strength. You have to fend them off by dropping crosses or using accumulated power for stronger spells, such as Freeze. What marks it out is the landscape.
Unlike most two player options the one in Realm of Impossibility is aimed at co-operation. It's a nice touch, and means that to improve your own best score you need to keep your opponent alive so that they can help you in turn.
Unlucky for some, maybe, there are thirteen of these caves, each needing to be loaded from the second side of the tap, and some remain locked and unloadable until the other levels have been conquered. Though multi-loads can be annoying this one means the game is big.
All of these features have made this a US top five hit and it's not difficult to see why. But - or should that be but - Ariolasoft's conversion is atrocious. As an object lesson in flickery sprites, bad control and the odd bug or three, it's excellent. Yes, it's just playable if you can put up with invisible (white on yellow) characters and severe steering problems. It's as if the programming had been done by people who knew nothing of the Spectrum's capabilities - and even then they'd done it in a hurry! This belongs in the Realm of the Turkey.