Gamesmaster focuses on his 'games' to deal with the constant thoughts flooding in his mind. He formed the Upstarts as one such way to entertain himself.
After the Upstarts captured several former New Mutants and took them to the Gamesmaster's base in the Swiss Alps, their teammates in X-Force and the New Warriors attempted to rescue them. They were easily defeated until Husk managed to convince him that letting them go would lead to better games. Gamesmaster allowed them to go and disbanded the Upstarts.
Later, Gamesmaster took possession of Doctor Weisman of the Weisman Institute for the Criminally Insane and one of its patients, Jeremy Stevens. The Institute had a history of involvement with Professor Xavier. He sensed something was amiss and sent Siryn to investigate. Gamesmaster clouded Siryn's memories, but she was rescued by Deadpool. Deadpool himself was captured but Siryn and Shatterstar freed him.
The Gamesmaster later watched as Shatterstar merged with Benjamin Russel.
Gamesmaster later attacked the X-Men. He isolated Jean Grey as the biggest threat and imprisoned her. The other X-Men were presented a vision of a utopian world as he sought to trap them. However, Joseph was able to distract him long enough for Jean to free herself. Gamesmaster was then defeated by the X-Men.
Recently, Gamesmaster has appeared in the X-23 one-shot, speaking to the young mutant about how he finds her particularly interesting and how he has been watching her for a long time. His motives in her regard are left ambiguous for now.
Gamesmaster makes a cameo appearance in the X-Men episode "Time Fugitives" (Part 1).