The "YandereDev situation" refers to the controversy surrounding Alex Mahan (known as YandereDev), the developer behind Yandere Simulator, a game that became popular for its premise of playing as a "yandere" (a character archetype in Japanese media representing an obsessive and often violent love interest). While Yandere Simulator has garnered attention since its inception in 2014, its development has been plagued by multiple issues, leading to extensive backlash and controversy.

YandereDev has been criticized for his interactions with his fanbase. On multiple occasions, he has lashed out at fans and critics on social media, leading to accusations of unprofessional and hostile behavior. Some of his responses to criticism have been viewed as defensive or rude, which has alienated parts of the fan community. Screenshots and logs of these interactions have circulated online, fueling the controversy.

Yandere Simulator has been in development since 2014, and as of 2024, the game is still incomplete, with no clear release date for the full version. This slow progress has led to frustration within the fanbase, with many questioning YandereDev's productivity and management of the project. Frequent updates were initially made to the game, but major milestones (like implementing all ten rivals) have yet to be completed, causing fans to lose confidence in the project’s future.