Cassell's channel achieved substantial growth, passing one million subscribers in June 2012 and one billion views in late 2013.

Cassell's YouTube content began to shift into vlogging, where his prominence in the genre took place from his life between Los Angeles and the UK.

Back in England, Cassell and his father designed his own home, purchasing a nearby property and renovating it into an extensive gaming area.

Cassell has co-founded a range of businesses, one of which failed to comply with Federal Trade Commission (FTC) advertising guidelines.

He co-founded the entertainment company 3BlackDot along with Evan Fong and Adam Montoya, and became featured in other media, spanning from a mobile game to a 12-track compilation album.

[3][11] He attended Hyde Clarendon Sixth Form College in Ashton-under-Lyne and studied software development and video game design in 2010.

[15] He then acquired a capture card in 2008 to record his gameplay, in which he was inspired by video compilations of no-scope sniper kills on Call of Duty from a friend.

[13][18] Cassell had amassed around 300,000 views on his Call of Duty gameplays when he received a contract offer from multi-channel network (MCN) Machinima.

[3][18][19] In October 2012, Eurogamer reported that Cassell had attracted the attention Call of Duty publisher Activision during a 2011 GameCity convention.

[4] Kevin Dowling of The Sunday Times recognized him as the UK's most popular gamer and estimated that he earned £700,000 a year, or £60,000 a month.

[20] Cassell co-founded the entertainment company 3BlackDot with YouTubers Evan Fong and Adam Montoya in 2013,[10][21] along with former Machinima executives Angelo Pullen and Luke Stepleton.

[28][29] Gamasutra later reported that Cassell uploaded Let's Play videos of 3BlackDot's game Dead Realm,[21] which failed to comply with FTC guidelines regarding a disclosure of a sponsorship.

[34] The FTC later reached a settlement agreement with Martin and Cassell in September 2017 for disclosing their legal relations and sponsorship deals with companies.

[16] Activision then collaborated with Cassell to showcase and stream the "Gunfight" multiplayer mode in Call of Duty: Modern Warfare (2019) on Twitch.

[44] He was aware of potential negative aspects of vlogging, such as showcasing "drinking and partying", although wished to remain as authentic as possible online.

Stepleton believed that the success of the game was primarily due to fans of Cassell, as they "put zero promotional dollars behind traditional user acquisition".

[22] Cassell voiced Loki in the mobile game Marvel Avengers Academy and was featured in the feature-length documentary film Minecraft: Into the Nether.

[18][47] Cassell was a guest star at the premiere of the Call of Duty: Black Ops III (2015) Zombies map "Shadows of Evil" at San Diego Comic-Con 2015.

That same month, Cassell was accused of sexual assault by Twitch streamer Natalie Casanova, known as TheZombiUnicorn, while the two were filming the Legends of Gaming show in 2016.