The Desire Sensor is a common myth in the Monster Hunter community, but apparently Capcom had at one point tried to make it an actual game mechanic.

According to 4Gamers Taiwan, Capcom had filed a patent for a system that measured player behavior, and adjusted material drop rates accordingly.

In theory this could have been used in a way to help players- if they saw you were farming the same monster too many times, it could have been used to theoretically increase the drop rate for rarer materials, reducing player frustration.

However Monster Hunter players are infinitely cynical, and would have no doubt blamed the Desire Sensor for their failure to get a Rathalos Ruby even after multiple runs since it apparently was also meant to detect exactly which items you’d need for that sweet Greatsword upgrade, and keep it away from you to keep you playing the game longer. Or worse yet, use it to blame their friends for getting their materials flawlessly.

In the report, it mentions that Capcom had filed the patent in September 2019, just after the launch of the Iceborne expansion for Monster Hunter World.

That means that the earliest we could have seen it in a game would have been in Monster Hunter Rise, though more realistically it might have been planned for Sunbreak.

Note that even though the patent had been filed, it doesn’t mean we can expect Malzeno to have fluctuating drop rates- patents are for ideas, not necessarily mechanics, and many patents can be filed but never implemented.

Meanwhile, the rumors of the existence of a Desire Sensor are so strong that members of the community had even created a parody Twitter account with the name.