Imperial Culture is an amorphous thing; each planet within the Imperium has its own local traditions, be they days of celebration, styles of dress or even local language deviations like slang. There are however some factors of cultural unity that are shared across the Imperium; there are celebrations, such as the Feast of the Emperor’s Ascension, that are shared even if they occur at different times due to adjustment for calendar shifts across over a million worlds, as well as certain aspects of design and architecture that are popular.
Any artist, actor or writer has to be very careful about how they express themselves; the Adeptus Administratum’s Censors are incredibly talented and efficient in their suppression and control of artistic rebellions, and have very little tolerance for deviation. Such is the paranoia and obsession of the Imperium with controlling its subjects, that even the most devout artist might occasionally have a piece censored and be reprimanded for something perceived as inappropriate.
For this reason the most popular schools of art take their cues from the Terran aesthetic that developed over the course of M.32 with the establishment of the Ecclesiarchy. Indeed, the Ecclesiarchy is largely responsible for most of the shared elements of Imperial culture. The Terran aesthetic is not dissimilar from the Gothic art style of Pre-Imperial M.1 Terra, focused primarily on reflections of the Imperial Faith through epic construction projects and monumental sculpture reflecting the visage of the Emperor, the Nine Primarchs or Imperial Saints and Heroes, and also through drawn work.
Faith and military victories tend to be particularly popular subjects, and portraiture is common, but romance and erotica do exist within the Imperium. Imperial art generally tends to reflect the socially conservative nature of the Imperium regarding open discussion and depiction of sexual acts, but such things are neither heretical nor illegal. The depiction of the Emperor nude, or Imperial heroes in romantic situations, is not considered slanderous so long as it is done with proper veneration of those involved. The Emperor and the deific heroes of the Imperium are, however, almost always displayed in the dominant role within these pieces. These art pieces are certainly likely to cause a few blushes, but they are not forbidden; indeed the Imperium would much rather individuals enjoy sanctioned art then turn to unsanctioned materials.
Within the Prosperitas Sector, due to so many Imperials having arrived on colony ships, the favoured form of art comes in the form of portable statuary and painted or fabricated imagery that can be carried easily on one’s person. Many individuals favour painted Icons that can be carried on an individual and there is a living to be made by artists who produce these small artistic pieces.
Fiction and nonfiction writings are still popular amongst the upper and middle classes of the Imperium, though rampant illiteracy mean that visual media in the form of “holos” or “picts” tends to be more popular with the majority of lowborn Imperial citizens. Real-paper books are things of considerable value, the majority of written pieces are either printed on recycled polymer sheets or digitally presented. Nonfiction works for mass consumption tend to focus upon military history, the lives of important Imperial figures and religious texts, often regularly re-published in new editions as the official Imperial histories alter with its governments and old editions are swiftly thrown into censor-pyres where they are found.
For this reason the majority of authors not working within the confines of scholarly institutions, or the Inquisition, tend to focus upon fictional works, where there is vastly more money to be made from a more receptive audience. Imperial fiction tends to focus on either utterly fictional protagonists or protagonists based loosely upon historical figures, more often than not serving as propaganda to teach citizens about dangers, or exhort them to aspire to a life in one of the Adeptus Terra or the Astra Militarum with tales of bravery. These pieces tend to be action-focused, but slower narratives like romances are equally as avidly consumed.
Education in the Imperium is poor and, as a result, many of its citizens are illiterate. Any other forms of the written and spoken word outside of the official state languages of High and Low Gothic are forbidden; for these reason the visual and audible medium are the most consumed form of art and media across the Galaxy.
Many famous stories are translated into audio and pict books for ease of consumption and these are the most readily available sources of entertainment due to the huge variance in technologies across the Imperium. On some higher-tech worlds a hab-block might cluster around a pict-viewer projected onto a hab-wall to watch broadcast dramas and propaganda reels – up in the higher echelons of society Nobles are generally better educated, but enjoy better quality versions of these productions, be that on the stage in the form of plays and opera, or via higher technology pict-viewers.
Beyond stories shared via audio recording or oral tradition, Imperial music is incredibly varied; the Ecclesiastical style is heavily reliant on organ and choir both of which are best appreciated within one of the great temples of the Imperial faith. Music and song are also vastly harder to suppress by censors, and so are often popular forms of rebellion in the Imperium, even if it is usually acceptably tame rebellion. Alongside orchestral and choral music, there are electronically produced pieces from venerated tones piped through the myriad voxes of many hive cities or on transports, there are the loud and discordant tones of Flip Music popular amongst Imperial Guard Troopers, highly popular amongst younger citizens for the adrenaline-pumping tones it produces. Ironically, although the Imperium now disapproves of it, Flip Music has its origins within the Astra Militarum as a psychological experiment.