The hype for Marathon has been building leading up to the free server slam event on February 26-March 3, with all that excitement coming to a head at the start of the Marathon free test weekend, which kicked off with a sizeable peak player count of 143,621 players just under two hours after the start of the event. Given that the server slam event started on a Thursday, it seems likely that many of the players who have since stopped testing the new extraction shooter had real-world responsibilities to attend to. Those numbers also only represent the game's Steam market share. Accounting for players on Xbox and PlayStation 5 would likely lead to significantly higher player count figures.

Despite this success, online discussions surrounding the new shooter seem to be surprisingly divided, with players both praising and criticizing Marathon for everything from its art style and UI design to the gunplay, lack of tension and PvP action, and the NPC AI being challenging. Character balance was also a common topic that featured in critical reviews, with some players complaining that certain characters are too overpowered while others are not capable enough. While some of these complaints, like the UI being difficult to read and certain performance issues, seem to be somewhat more widespread and valid, the Marathon development team at Bungie has responded to and acknowledged almost all of the common complaints in a recent post on X, either offering some advice to improve the player experience or requesting more detailed feedback so that issues can be dealt with ahead of launch or in post-launch patches.