@Waawo
Glad you liked it! I definitely think that it's a book that could do with re-reading; there are a lot of mythological and magical references packed into what is a relatively short novel, all things said, and I think it can be easy to perhaps overlook some things.
SPOILERS
On first read, I have to say the ending feels a little weak. But I think the metaphor of the game being really just life is very clever. "Beware, every action you take in the game can have an effect in life": well, yes, in the 'game' of life that's true! So perhaps the apparently entirely non-supernatural conclusion is inevitable.
I have a different perspective; in that I don't think the metaphor was meant to be that the game was just life - but more that it's exactly what's said in the novel that the game (and the dice) are artefacts of some kind of magic which influence what happens in life. But the magic in the novel operates (and appears) subtly and invisibly. Hidden in plain sight, if you will.
Here's a quote from Roger, the author, himself, from my correspondence with him a few years ago which may shed some light on his thought process:
"I’m edging towards my own attempt to roll up the matter of Britain and the Arthurian cycles and the ancient secrets of the Island into a work of fiction, and I should say at once that your idea of the game as a ‘bridge between the worlds’ is exactly what I had in mind. If the Caer Sidh (which seem to have various spellings) are locations on the surface of the earth from which the otherworld or underworld can be accessed, then the Game with its charmed dice is also a key to the gate, as Doctor Death recognized. As others have done, he took literally what should have been understood metaphorically, ending up speechless at the bottom of a pit."