[Warning: Spoilers for Marvel's Guardians of the Galaxy (2021) below.]
In Marvel's Guardians of the Galaxy, Drax the Destroyer completed his ultimate goal and killed Thanos before his adventures with the team began. In one of the more shocking story beats, Thanos isn't the big threat in the new Square Enix video game but is already supposedly dead when the story starts. Drax brags about defeating Thanos throughout the game, which was his biggest goal in both Marvel Comics and the MCU.
In the comics, Thanos is responsible for the death of Drax's wife and daughter. In the tragic tale, the Mad Titan kills Arthur Douglas' family after thinking they saw his spaceship during a scouting mission on Earth. Ultimately, Thanos' father, Mentor, would choose Douglas to become the ultimate weapon against him, turning the human into Drax the Destroyer. Drax has tried to kill Thanos on multiple occasions - and has done so before. In the MCU, Drax's origin is changed quite a bit. However, Thanos being responsible for the death of his family is still a driving factor in his motivation to stop the villain.
In Marvel's Guardians of the Galaxy, the game blends the hero's personalities seen in the comics and MCU. Drax is a great warrior and the muscle of the Guardians but keeps his dry and unintentionally humorous personality seen in James Gunn's films. In the story, Drax tells Peter Quill about how he defeated Thanos. Drax reveals that after his family died (like in the comics), he was given powers by Mentor and Kronos. On the Black Quadrant, he found Thanos hiding. The two engaged in a days-long battle, where their powers equaled one another. Drax delivered one last blow to Thanos before passing out due to sheer exhaustion. When he woke, he was hailed a hero by the rest of the galaxy.
Marvel's Guardians Of The Galaxy: Could Thanos Return In The Sequel?
Despite celebrations that Drax defeated Thanos, he still doesn't believe the villain is dead. He tells Star-Lord that he still feels the Mad Titan's pulse across the galaxy during the same conversation. This potentially opens up the possibility of Thanos being in the GOTG sequel - if a second game should release.
Ultimately, Thanos' looming presence builds tensions throughout the game. Drax revealing that he is not fully convinced the Mad Titan is dead sets up quite an interesting potential future for the series. While Thanos doesn't reveal himself by the game's end, Marvel's Guardians of the Galaxy strongly hints the supervillain's story isn't done. Whether Thanos is alive and appears in future DLC or in a sequel, Drax the Destroyer will likely try to kill Thanos again at some point - even if everyone else thinks he's dead.