I've sometimes been asked about how I handle such things in my campaigns, particularly those in House of Worms. Even before the recent unpleasantness, Tékumel long had a reputation – somewhat undeserved in my opinion – for being a particularly brutal setting that included lots of aspects of pre-modern societies that, while perhaps "realistic," are usually glossed over, if not outright excluded from games like Dungeons & Dragons. The same, too, could be said of almost every RPGs whose setting is a time of war or strife, whether that setting be pre-modern, modern, or futuristic. How does one referee a campaign that contains such dark elements?
As with most aspects of my refereeing, I don't have any systematic answers, only anecdotes and examples. However, looking back over what I have done does, I think, provide something approximating an overarching philosophy that might be of use to others referees whose campaigns deal with such things. For example, let's look at a ubiquitous and indeed foundational aspect of most of the cultures of Tékumel: slavery. Abhorrent though it is, slavery is commonplace throughout history. Indeed, there's scarcely a human society that hasn't practiced slavery at one time or another. Though a fantasy setting, Tékumel draws on several real-world cultures for inspiration, like ancient Egypt, the Aztecs, and Mughal India, all of which practiced slavery, hence its inclusion in Empire of the Petal Throne.
The player characters of the House of Worms campaign are thus all members of a slaveholding culture and do not question the practice. Their clan owns slaves and at least a couple of PCs have had personal slaves who became important NPCs (though one was later manumitted and adopted into the clan). Despite this, slavery has never been important part of the campaign. It's part of the "furniture" of the setting, something that's undeniable there, but that we've never really dwelt upon, because the focus of the campaign has always been on adventure, usually out in the wilds, far from any Tekumeláni civilization.
Similarly, the major cultures of Tékumel all approve of human sacrifice to varying degrees, as have many cultures on Earth. The god most of the characters worship, Sárku, accepts such sacrifices as part of his rituals and so priestly characters have occasionally been involved in them, too. The same is true of the torture of prisoners, which is seen as a legitimate form of interrogation in Tsolyánu and elsewhere. So, again, these deeply repugnant elements of the setting have appeared from time to time, but they've never been its focus. When they have appeared, such as during attempts to invoke divine intervention (for which there are rules), we'd simply acknowledge it and move on – the equivalent perhaps of the cinematic "fade to black" of old.
I could cite plenty more examples from both House of Worms and Barrett's Raiders, but I trust that's not necessary. What I have come to realize is that, unless it's absolutely relevant, I don't spend a lot of time going over the finer details of all the unpleasant things that happen in my games. This includes combat, by the way, which, as players of many old school RPGs know, is generally very abstract. Now, there are indeed times when the precise nature of a horrible injury is relevant – this has come up several times in the Twilight: 2000 campaign – and, in such cases, I don't shy away from the gory details. However, as a general practice, I avoid doing so, because my games are meant to fun escapes rather than luxuriating in the darker corners of the human soul.
I offer my experiences not as a universal prescription. Each referee and player will draw his lines in different places and that's as it should be. I personally feel that there's generally nothing wrong with including unpleasant realities in one's roleplaying so long as everyone's on the same page in this regard. I don't fault anyone who wants to keep his games "family friendly," but neither do I condemn anyone who wants to venture farther into the shadows. One of the things that's great about roleplaying is that it's a flexible enough entertainment that it can accommodate both approaches – and more besides – without any difficulty.