Level Fun is an anomalous level of the Backrooms, and is widely known for being a safe haven of - and potential origin of - the Sanguine Festivus virus.

Following the events of the Flicker, Level Fun's layout consists of a vast and complex network of rooms and hallways adorned with wallpapers of wildly variating colors and patterns. Most of this level is furnished with decor commonly found at party venues, often suited for children's celebrations in particular. Dining and picnic tables lined with plastic chairs populate almost every room - sometimes in such high numbers that it's difficult to navigate - many of which packed full of food, drink and messily-wrapped gifts, while others lay overturned or even broken into pieces. Balloons can be found practically every five feet within this level, either in physical form or in the form of wall patterns and paper decorations, often numerous enough to nearly overwhelm rooms and obscure the ceiling. Similar decor can also be found throughout the level in the form of colorful streamers and banners, strewn-about scraps of confetti, party games or arcade cabinets often dirtied or broken, and haphazardly laid-out mats of vibrant mismatched shapes and colored checkerboard patterns.Food and drink found in the level is often described as questionable in appearance, being sickly or off-putting in color or left smeared, spilled, or otherwise unpresentable. Despite this, many wanderers who've successfully returned from exploring Level Fun report this food to be more often than not edible, albeit usually having a peculiar aftertaste of rust or meat despite the ingredients of whatever is consumed.
Those who enter this level often note the constant sound of music from one direction or another, near or far, with its origin never quite being apparent. The music heard varies wildly from report to report, ranging from piano melodies to blaring swing music to upbeat yet dated pop songs, often inescapably accompanied by the sounds of people talking, cheering, laughing, or screaming. In fact, it seems as though finding a quiet section of the level is nigh impossible according to explorers' accounts.EntitiesSeveral lower sections of Level Fun are noted as being partially flooded, with stagnant gray water spanning the length of entire rooms. Depending on the elevation of the room, this flooding can range from a puddle's depth of less than an inch, to complete and utter submersion. While a variety of refuse and pollutants is often found in this water, the foremost contaminant it contains (and the reason for its discoloration) is the Sanguine Festivus virus.

Photo of a flooded room in a low section of Level Fun. Note the discoloration due to contamination.

While contact with the water is not a guaranteed hazard, infection is still a tremendous threat for those who attempt to wade through these waters. If any contaminated water is ingested, inhaled, or comes into contact with the eyes, nose, ears, or an open wound, then transmission of the virus is almost guaranteed. Wanderers are urged to avoid contact with the water at all costs and to assume infection has occurred and act accordingly if exposed in any of the ways listed above.
Inhabitants of Level Fun (see below) are also known to bottle water from these low sections and leave it amidst other food and drink on tables throughout the backrooms game level. While a keen eye can identify the discoloration - as it is usually quite distinct amidst other beverages found in the level - wanderers are nevertheless urged to avoid drinking anything from an opened or unsealed container. Contaminated water is often odorless and tasteless, and if mixed with other beverages can be nigh impossible to detect.
Due to the sheer abundance of the virus in Level Fun, many wanderers - particularly members of the Party Crashers - have theorized that this level might in fact be the origin of Sanguine Festivus. Theories as to how the infection began to spread pose that the first known victim of SFV, Caius Taggert (AKA the "Party Host"), may in fact have been the first person to find their way to this level and contract the disease. Short of attempting to ask Taggert himself, however, this in unconfirmable and therefore remains speculation.
Besides the prevalence of Sanguine Festivus, no other entities of any form can typically be found in Level Fun.