Did we mention that the Unterzee is dark? I think it may have come up once or twice. Paul's already talked about the importance of light and darkness in the aesthetic. I wanted to outline some of the ways we're baking it into the game mechanics.

When you first leave Fallen London, the zee is cloaked entirely in the darkness of the unknown. As you might expect, once you've seen an area it's no longer unknown, and it'll appear on your map, and dimly on the screen where your light isn't directed.

Fortunately you have a powerful prow-light to strip away the darkness and reveal coastlines, islands and other features. But this glim-light requires fuel to run - so you may wish to turn it down to preserve fuel, or even turn it off entirely. Without your prow-light, you've still got a limited circle of illumination around your ship - enough to explore slowly and cautiously - but it'll be harder to plan your progress.

So there are advantages to clearing the darkness-of-unknown as quickly as possible: you may not be able to make out the details of zee-monsters in the revealed areas, but you'll have an idea of the landscape. There's another advantage, too. Clearing darkness-of-unknown (as we discussed here) gradually gives you the Zee-Ztories and other knowledge resources that you can sell to supply your missions, or convert to Secrets to purchase crew upgrades.

And there are disadvantages to keeping the lights too low. We track the total light in your immediate area - influenced mostly by your own ship's lights, but also by the tile environment - and use it to determine Gloom. A high Gloom will have a gradual but major effect on your crew's Terror. A low Gloom, as you return to brighter areas, will gradually decrease it (as will shore leave, judicious use of Zee-Ztories, and cracking open the brandy). As your Terror rises, it'll trigger stories of nightmares, madness and worse, taking a toll on your Crew. Up to a point that's all good clean fun, but let it rise too high and it'll be your ship that some poor soul in a first-person horror game stumbles on twenty years later. "Look at this!" they'll say as they find another diary page in a closet full of monsters. "Can you believe they left the lights off through all this?"

So is more light always good? Not quite. Aside from the fuel costs (and you really, really don't want to run out of fuel and be left motionless in the dark), your prow-light can wake monsters. Beasties (our general term for sea-monsters, enemy ships and other autonomously moving things) will wander and hunt whenever active, but when you get too close - or when your light touches them at a greater distance - they'll switch to a more aggressive and alert mode. In dangerous areas, you may want to keep your lights low to avoid attracting attention...

And you do have one more tool at your disposal to help locate terrain: bats! You can purchase caged zee-bats for your ship, to release and return with news, after the manner of Moses' raven. In game terms, this means a pause until your bat returns and tells you the approximate direction and distance of the nearest land-mass - just enough to stop you sailing right past something interesting. We may allow upgrades to bats which can tell you more detailed information - it depends how much resource we have spare, and how much you folks like the idea.

Next post: the geography of the Unterzee. And a couple of actual screenshots of the prototype to illustrate it...