Two people could play it at once, which was revolutionary at the time, and stopped my brother just punching me until I gave him the joystick. 2-player RPGs are brilliant (my wife and I had a blast playing through Balder's Gate Dark Alliance - certainly more fun than watching me ride my horse around Oblivion for hours at a time).
This is the bit where you choose your characters. My brother, of course, took the cool looking knight guy, the cool hooded wizard guy, the hot blonde chick and the cool looking ninja guy. That left me with a blue hermaphrodite thing, Sinbad, a smurf and a f***ing lizard. I didn't care though - this was the coolest thing I'd ever seen!
You can scoff at the graphics all you want, but most people were still playing 8 colour C64 games, so this is basically the f***ing Matrix. My brother soon found that he could threaten to beat me up inside the game unless I gave him all the best loot: basically he invented cyber-bullying 10 years before there was a word for it. I specifically remember one of my guys having to fight with a chicken drum stick.
We played Bloodwych every day and within a few months we had completely worn out the disk and both of the Atari's notorious joystick ports, so we never got to see the cool looking monster on the cover art, which probably wasn't even in the game because cover art was just lies back then.