I thought this variant up myself, but after I thought of it, I also saw a reference to it as a modification of Mastermind in a journal paper somewhere. The idea is that after Player 1 submits their guess, Player 2 submits their guess and also has the option of choosing the number of black and white pegs seen by Player 1 for their guess (so the response could be a lie). Each player would only get one lie per game. Also, obviously if the code was guessed correctly, no lie could be used.
(verberg) Als u op uw beurt aan het wachten bent en niet steeds op F5 wilt blijven drukken kunt u ook de pagina snel automatisch laten vernieuwen door op "Verander" naast "Verversen" te drukken op de Hoofdpagina, en de tijd hier in te stellen op bijvoorbeeld 30 seconden. (Servant) (laat alle tips zien)