I think you should not look at it from the moral point of view. But from the "what player is going to do/player's morality" point of view.

For example, in case of a game when you run a sugar plantation and you (the player) is personally going to whip your slaves, well, it's kind of outrageous :) But when you have a game like Victoria 1/2 where you have those slaves as an abstract category of population and the player is not catching those slaves and not doing anything bad to them and even have an option to free them, well, it's completelly OK.

It's nice to see so many moral people, but let us not forget about the players who install Fallout and Skyrim mods just for the ability to kill the children NPCs along with the adults. In games, players don't always make the moral choice, and that's why we have the thief class. From a game stance, slave trade isn't too different. Both are usually deemed immoral and can get the character in trouble, as well as a risk-reward system. Just like a thief has a chance to get caught pick pocketing, a slave trader in the game may have a chance of a slave mutiny on his or her ship. It doesn't have to be glamorized, or a major focus. A play can buy and sell trades in certain ports, but may not be allowed to in others (as was the case some times). If a mutiny happens, the player suffers a loss of something, perhaps valuables. If you're still worried about the controversy of a historical economy, try making it an option for the game to be played without the slaves (I've seen many game manuals tell of other ways to play the game, this won't be much different).

It's nice to see so many moral people, but let us not forget about the players who install Fallout and Skyrim mods just for the ability to kill the children NPCs along with the adults. In games, players don't always make the moral choice, and that's why we have the thief class. From a game stance, slave trade isn't too different. Both are usually deemed immoral and can get the character in trouble, as well as a risk-reward system. Just like a thief has a chance to get caught pick pocketing, a slave trader in the game may have a chance of a slave mutiny on his or her ship. It doesn't have to be glamorized, or a major focus. A play can buy and sell trades in certain ports, but may not be allowed to in others (as was the case some times). If a mutiny happens, the player suffers a loss of something, perhaps valuables. If you're still worried about the controversy of a historical economy, try making it an option for the game to be played without the slaves (I've seen many game manuals tell of other ways to play the game, this won't be much different).

This was IMHO handled quite well in fallout 3.

They had a slave trade and you could join with the slavers from paradise falls and enslave people, putting bomb collars on them.

Of course it had its issues. As well as massive karma loss from dealing in slavery everyone would hate you. Doors which were previously open would be closed (metaphorically speaking) and those willing to trade and talk to you might just now be hostile on sight making various quests simply unavailable to you.

I wouldn't say slavery was glamorised in that game but it did provide a different plot line.

The difference I think was that slavery there wasn't racial in any way like historically accurate slavery has often been and this is why it was tolerated in game...

I think it is a deep mistake for players and designers to expect a 1:1 correspondence between gameplay mechanics and real life. In all our time gaming (tabletop / board game or electronic) how many innocent lives have we players all taken collectively? How much have we stolen? How many have we wronged?

If we are talking about fictional entities the answer can only be zero. These things do not exist. They are not real. Therefore no living thing can be harmed, and what kind of creatures are we if we are obsessed with the morality of deeds against non-living, non-existent things? At best we can be accused only of committing crimes of the imagination.

I agree with the point others have made that some will see your work as taking a position, and I feel we currently live in a time where being seen to be moral is perhaps more important than actually BEING moral. If position is a concern, I'd simply make it clear in the manual that this was historical fact and its inclusion is neither meant to condone nor glorify and leave it at that. Some people will nonetheless be deeply offended. It is their right to be so, and it is your right to ignore them. Let them create works that promote their own values. Maybe your work can serve as a springboard for a game about abolition or a deeper simulator whose mechanics plumb the depths of the psychology of objectification.

As an aside let me also note that a rising interest in injecting modern morality into gaming isn't in and of itself a bad thing. There are wide open frontiers to explore in that direction. But a game is not somehow immoral because it incorporates distasteful and even downright evil subject matter. With gaming we must resist the mechanism in our brain that correlates thinking about something as doing it. Thinking is thinking. Doing is doing.

Thinking is thinking. Doing is doing.

Unfortunately the lines are being blurred between real crimes and "thought crimes".

How often do you hear on the news of someone being charged for "planning to commit" a crime? They were only thinking about it, but proof was there they were planning to do so, and "going equipped" perhaps.

It's worth remembering that if people think your game encourages the behaviour depicted in it, it can be harmful to you, your business if you have one and your reputation.

On one side of the scale is rockstar games and the content of the gta series for which they are regularly panned by the media, and on the other side many smaller game studios without as much of a legal team who you haven't heard of because they faded into obscurity due to a risky game theme.

I suggest treading wisely even if you are feeling idealistic...

You could do some research on traders of the Era, and see if there were particular organizations at the time that prohibited slave trade.

You could represent slave trade as a system challenge that competes with your trade while the players work to trade outside of slavery.

You could also include it as a derogatory choice which has easy gains but steep penalties. The problem is, I don't imagine that's an authentic representation of the trade.

Personally, I'd avoid a game about slave Era trading, it might hold some facination, but market wise, seems like an impractical liability.

TBH, treating slaves as a commodity and simply a trade "good" would likely rub people the wrong way, and garner a lot of negative publicity and lost chances for sales. That really just glazes over the whole issue entirely, and dehumanizes the slaves into the same level as a crate of bananas or barrel of monkey oil. Even if you model deaths and suicides in, it's going to come off the same way as if several crates of food spoiled or was tossed overboard during a storm.

When thinking of writing in a delicate subject, first ask "Am I being respectful of what these people went through?" Then ask, "does this add to the story and/or gameplay?" If the answer is not truthfully 'yes' to both, don't put it in game.

I have a scripted instance that could result in a rape (depending on whether the player acts to intervene or not), and another quest line that features slavery. But, in the first case, it's more providing the player with a definite choice with consequences, as you will see later the results of your inaction. The latter I'm not happy about, and may cut it even though it would fit with the setting and overall story. In short, the player is investigating missing persons and stumbles across a slavery ring operating in a refugee camp. In this case, you see the results of not investigating and dealing with the issue more at a distance, as you're not really introduced in any fashion to the victims unless you choose to follow that quest line. I'm not happy about that, as I'm not sure how to push forward the sense of what happens if you don't care about these people. Even if they're not real, I want the player to feel a sense of unease just leaving them to their fate.

In both cases, if I do not feel that the characters in both arcs are humanized enough, I'll cut them entirely. The former is in a much better position, as you meet the NPC and others around them repeatedly, but the latter so far is just to distant from the actual people involved.

In your case, it looks more like 'slave' is just another line item in a list, which comes off unintentionally as dehumanizing. And given your gameplay, I'm not sure how you could humanize the slaves given that you're operating at a more abstract level anyway, and not really driving a heavy narrative.

it looks more like 'slave' is just another line item in a list

It's only the historical accuracy and the fact it imitates life that makes it more offensive to people.

Imagine a game concept where you're an alien civilisation and you trade human slaves, regardless of race, colour or creed.

You can almost guarantee nobody would bat an eyelid because it's not something so close to real life...

it looks more like 'slave' is just another line item in a list

It's only the historical accuracy and the fact it imitates life that makes it more offensive to people.

Imagine a game concept where you're an alien civilisation and you trade human slaves, regardless of race, colour or creed.

You can almost guarantee nobody would bat an eyelid because it's not something so close to real life...

Or bat an eyelid trading slaves in ancient Rome, Egypt, or any other ancient civilization, where slavery wasn't based on (as visible an extreme of) skin-color.

I think it's the combination of: it was only 150 years ago, and the effects were still significantly felt as recently as 50 years ago, and there's still some discrimination ongoing, and the people-group who was enslaved are still mostly in poverty.

If blacks were now mostly very well off and prosperous, I think it'd be much less offensive, even if it had happened only twenty years ago. But it's a combination of "yeah, life still sucks for us" (relative to the USA average) and the nearness in time that makes it particularly odious.

if you want some real historic content, you also need to include things like :

- the carribean was known as the 'white mans graveyard' (same more than a few other colonial areas) because of the death rate from tropical diseases killing like half the europeans who went to live there.

- because of the value of the economy there were more than a few wars to try to grab others territory

- Pirate/privateer activity

- political machinations to maintain the sugar monopolies by the rich families involved there

- the constant threat of slave uprisings

- trade monopolies for secondary goods maintained by the mother country

-natural disasters (including things liek an earthquake that destroyed much of a major town)

- the religion factor

- indenturing of white 'slaves'

- mixed race populations