There is a Conflict for some people if the are for games or not ... BUT there is no conflict if they have amazing imaging/positioning and that are a little better on soundsatge from 600 and 650 and thats because of the airiness that they have .
So in the end do they have better sound stage do they have better imaging are they better at games compared to HD 600 and HD 650 ? YES YES YES ....
Are they amazing on Gaming ??? NO and YES ... these HD 6 series are known for the close to head music stereo perfomance thats what they are best for , can been used for games ? yes they can and honestly they are better than most headphones that i have heard .... BUT
There is a big BUT .... Most gamers doesnt want this HD 6 series sound profile , Most gamers need a V sound Headphones , closed or open with HUGE soundstage and emphasized highs so they can hear footsteps .
To me there is no Perfect headphone for games and Music ... There are headphones like HD 600,650, 660s thata are perfect for Music with small differences and there are Gaming headphones that have way different sound profiles .
My advice is if u want Gaming Headphone then u should Buy HD 599, Gaming One, DT 990pro , TYGR300, DT770, depending your needs and taste on sound signature or just STAY with HD 598 that Have way better Soundstage they have drivers that are angled and more far of the ears they have Sennheiser smooth signature with some more excitement for games and lets not forget the COMFORT of the HD 5 series they are by far the most comfortable with low pressure nice velvet soft pads (some series have fake leather )
Personally i use HD 6 series for music and 5 Series with games ... So i think u get it now No conlifct for HD 6 series any more