grimwerk: I used to play with my Grandad when I was young. He would leave pegs out and treat 'empty' as an extra color. My son saw Mastermind in a shop a few days ago and expressed an interest. (Without any prompting from me!) I meant to go searching for a set online. I'll do it now.
Me and my brother used to play a lot as kids.
So, we're now at:
purple green aqua purple black
blue Answer: 0 black, 3 white
yellow
purple green red
blue aqua Answer: 1 black, 4 white
green purple red yellow white
aqua Answer: 0 black, 4 white
So we know blue (presumably?) should be in the final set along with yellow and red.
There is no white or black and no more than 1 purple (which isn't the second peg).
And we need to lose one of either green, purple or aqua.