Long had been writing since the age of twelve, and upon breaking into the industry, proceeded to write screenplays for fifteen years. His work resulted in three films and many animated and live-action TV episodes. He has been living in Los Angeles for the past twenty years, and continues to write from this location, as well as playing regularly with his band, MI-6.

The Blackhearts

Long is responsible for a set of infamous characters in the Warhammer Fantasy universe,; the Blackhearts. A gang of renegades and rebels thrown together by unfortunate circumstances, they are given the choice of being hanged for their crimes or completing secret missions, both highly classified and suicidally dangerous. There have been three novels, now published in an omnibus along with two short stories, one serving as a prologue for the situation in which the novels are based.

Gotrek and Felix

When King stepped back from Black Library authorship to pursue other projects, the ongoing narrative of Gotrek's quest to seek out his doom was, as yet, unfinished. Black Library then approached Long, at the time a newly established but popular author in the Warhammer Fantasy universe, and asked him to take up the position of storyteller. Since the release of Orcslayer, Long has written four additional novels in the series along with an audio-book, making it one of the longest-running Black Library runs in the imprint's history, along with Dan Abnett's Gaunt's Ghosts series.

Long has been both hailed and criticised for his writing style differentiating substantially from that of King's, who was known for very flowery descriptive text and extensive description. Long, however, writes with pace and emphasis on the brutal side of the two traveller's lifestyle. Long has also been quoted in an interview as stating that he has "a rough idea" of how Gotrek's eventual death will occur, though audiences may assume this will emerge sooner rather than later, due to the naming format of the books (each a combination of a race or role, and the word "slayer") and the limited amount of races and roles left to cover.

Long was also one of the first few authors to publish an audio-book for the Black Library imprint, titled Slayer of the Storm God. Along with several short stories (mostly exclusive to events held by Games Workshop), these have helped fill out the universe immediately around Gotrek and Felix.

The latest book in the series, Zombieslayer, is due to be released in November 2010. On February 9, 2010, Long announced via his Sabrepunk blog that he had finished the rough draft.

Ulrika the Vampire

In addition to his work on Gotrek and Felix, Long has also written Bloodborn, the first novel in a series surrounding Ulrika, a love interest of Felix Jaeger in the Gotrek and Felix novels who has become a vampire and is learning to cope with her new form and its wants and needs. Bloodborn was released in June 2010, and is to be followed by a sequel, "Bloodforged", the front cover of which appears on the inside front cover of "Bloodborn".

Long has also contributed to Black Library's range of novellas, with a short novel titled Battle for Skull Pass, which was released in 2008 and was available exclusively to Games Workshop customers. The novella was based around the Dwarfs and their battle to save the township of Karak Grom from greenskin invaders. It was written to accompany the Battle for Skull Pass box set, released by Games Workshop.