In general terms, a video game is considered dead  when it's no longer played by the general public. This is especially true in MMORPG games, where active player participation is the lifeblood of the game itself. If you don't have anyone playing, there's nothing to play, even if you wanted to.

phrasal verb\n\n : to find a place for (someone or something) in a schedule, plan, etc. I can slot you in at 2 p.m.