The only thing that may be different about "gaming" headphones is more design consideration to long term comfort and a mic. All over ear ones will be good at sound isolation.
I used a pair of Steelseries 650 headphone for a focus group play test and they were like wearing a pillow, it was amazing. But they're not really what you're looking for.
In that case just get a decent set of over ear headphones. A lot these days even have a mic built in if you need one.
eg.
http://www.richersounds.com/product/all-headphones/akg/k451/akg-k451
The only thing that may be different about "gaming" headphones is more design consideration to long term comfort and a mic. All over ear ones will be good at sound isolation.
These Sennheisers are popular:
http://www.johnlewis.com/sennheiser-hd-558-full-size-headphones-with-e-a-r-technology-black/p1756614?sku=234116001&kpid=234116001&s_kenid=fa08906f-2cf2-4939-a7bc-860156644a50&s_kwcid=402x355810&tmad=c&tmcampid=73
But I would go for the Bose Soundtrue for that money
http://www.johnlewis.com/bose-soundtrue-ae-ii-full-size-headphones-with-in-line-mic-remote-for-samsung-android-devices/p2203293?sku=234682423&kpid=234682423&s_kenid=fa08906f-2cf2-4939-a7bc-860156644a50&s_kwcid=402x1088766&tmad=c&tmcampid=73
I used a pair of Steelseries 650 headphone for a focus group play test and they were like wearing a pillow, it was amazing. But they're not really what you're looking for.