I loves me some 99p bargains on eBay.
A replacement copy for the 15th birthday present that has since been lost to posterity (typical late 80s GW hardback - fell apart within six months and ended up being bound in a ring binder).
I'd say that Stormbringer is my favourite, least played RPG. I never got to play it until going to uni for a couple of reasons - all my mates loved WFRP and whilst I was a huge Moorcock fan in the 1980s, nobody else I knew was. They liked... erm Dragonlance.
So what do I like about this? It's all basic BRP stuff with a daft random character generation system that can end up forming parties with crippled beggars from Nadsokor and sorcerers second-in-line to the throne of Pan Tang with no thought given as to how to make this work but my love for this game is down to one thing - there are no conventional spells.
All magic has to be performed by summoning alien beings and bending them to your will. Fireballs? Forget it, you have to summon up Fire Elementals and command them to dash themselves against your target (there is literary precedent for this when Elric does precisely this whilst hunting down his cousin Yyrkoon). Travelling by magic? No simple teleportation spells in Stormbringer, instead you summon up a Demon of Travel and then tell the GM what form it takes. So if travelling from one part of the Young Kingdoms to another by demonic means it is up to the sorcerer to describe an airship, a submarine, being carried in the claws of a giant bat or similar. Excellent and inspirational stuff that lends itself much more towards player-involved subcreation than the simple Magic Missile.
I did buy Elric! (the 90s version of this game) but that turned away from this ground-breaking approach and went over to conventional spells. Not the same game, sold on eBay in the early days.