When you go to purchase Omori on a platform like Steam, you'll get a content warning that explains that the game might not be suitable for players of all ages. 

“This game contains depictions of depression, anxiety, and suicide, and may not be suitable for all audiences," the warning states. "It also contains bright flashing imagery that may cause discomfort and/or seizures for those with photosensitive epilepsy. Viewer discretion is advised.” 

In addition to these formal warnings from the game's creators, users on Reddit have also documented their experiences with the game, saying that the horror elements it plays with are more focused on invoking feelings of anxiety and dread and less focused on anything particularly gory. The Reddit users also said that the game featured some jump scares, which may be triggering for some players.