When purchasing a computer game, the disc should be included right?

[StickEmWithThePointyEnd]

And it would be fair to assume this is the case, unless the item description specifically says otherwise?

Well, yes, unless it quite clearly states somewhere in the listing that you are bidding on the case only.

The description states:

Limited Edition Steelbook. Used condition - a few scratches nothing to bad. I am a Steelbook collector/seller and the item will be packed well to avoid any damage.

Reading the description now I can see that the seller hasn't specifically said the disc is included but imo when buying a computer game you should be safe to assume the disc will be there, unless it says it isn't.

I've opened an item not as described case but wanted to make sure I'm not the one being unreasonable here!

Yes..seems useless otherwise!

of course you would expect the game to be included - what does the seller say?

Nothing as yet, waiting for a reply. I work with insurance and am used to reading policy booklets and t&cs so I have been analysing the description for anything that could have given me a clue that the disc wasn't there.

I never thought my job would affect my life this way...

Surely the scratches mentioned are on the disc so fair to assume it to be included

I'm pretty sure there is an eBay rule that a branded box cannot be sold without its contents.

This has been discussed a lot recently on the eBay discussion boards, as there are people currently selling empty iPhone boxes for hundreds of pounds.