Complex sentence: In 2010, he became a member of alternative hip hop collective OFWGKTA also known as Odd Future, and his debut mixtape, "Nostalgia, Ultra", was released to critical acclaim in 2011.
Split into simpler sentences: In 2010, he became a member of alternative hip hop collective OFWGKTA, also known as Odd Future. Ocean subsequently released his breakout mixtape, "Nostalgia, Ultra", to critical acclaim in 2011.