I found the overall visual design effective at evoking an eerie mood. The choice of muted greens and grays works to make the rays of lights (whether cast by your ship or emitted from various lighthouses) pop. Cruising in the dark of the Sunless Sea builds a sense of dread and mystery which is appropriate to the theme of the game.
Furthermore, the music, while infrequent, punctuates the mood and builds tension. The spare sound effects, the lapping of the water and the distant ringing of buoys create a soundscape on which your journey unfolds.
Much of the game takes place in a text window that is inexplicably tiny and stuck to the bottom of the screen. The prose comes in relatively short and disgestible tid-bits, so while much of the game is reading the stories you come across in your voyage, I didn't feel overwhelemed with a wall (or in this case a yard sign) of text at any point.
The stories themselves are full of mishmashed details and themes, making them far more colorful and dynamic than the graphics of the Sea itself. To me, the highpoint of the game was in unravelling these stories, bringing in various objects discovered along the way to open up new options. Leaving port and returning after a brief delay will advance the stories, so in this way, one can plan a route to satisfy different story requirements and continue to push back the fog of unexplored areas.
The game describes itself as a Rogue-like, which is partly true, in that some of the islands appear in different locations on each playthrough and there are some that may not be present at all. However, the area around London (the starting port) is always the same and this expanse of sameness can make the Rogue-like description seem like a fib. Death is easy when first learning the game, as it is in many Rogue-likes, so sailing through the same staring area again and again becomes tedious.
This leads to the first of my two major objections to the game, each shortcoming reinforcing the other.
1) Travel is at a decidedly deliberate pace. While this initially worked to make me savor exploration, as well as building a sense of anticipation or dread as I advanced through a game, the thought of sailing past the same islands that I'd already been to several times, in hopes of discovering something new seemed more like a chore and less like fun.
Before I stopped playing the game altogether, I'd plan out a route and make a loop, visiting some familiar places for resources or to advance a story and (hopefully) uncovering something new on the map. When I'd first began playing, I'd make three or four of these voyages before logging off (Assuming I didn't die). But the thought of just sitting for several minutes at a time, waiting for something to happen made me think I'd be better served quitting and loading up something faster paced after a few play sessions like this.
Until you've figured out combat (my second objection), it is very easy to wind up dead and have to restart and travel laboriously through regions that are largely unchanged from one game to the next. This makes for far too much travel time for my taste.
2) Combat is horrible.
Okay, I'll write a little more on this.
The various monsters and pirate ships are imaginatively and effectively rendered in the game. Many of them, however have a ridiculous number of hit points compared to the damage of any weapon that you will acquire before half the map is explored. That's a lot of traveling and, hence, a lot of game time.
To make things worse, the sound effects of the cannons are repetitious and obnoxious. When you're fighting a Lifeberg (an enemy that is easily encountered on your first voyage) that has 400 hit points and you're doing 15-20 every shot... not only does the same cannon fire sound grate on the ears, but the combat itself becomes a grind.
While there are a very few enemies that seem to be balanced around your starting equipment, it is easy to run into foes that are far stronger. When you add in the very slow late of resource accrual, it's not hard to wind up behind the firepower curve. When first playing, this can result in many deaths, which equal restarts, which means more tediously slow sailing through regions you know by heart.
Of course, you can avoid most of the fights, but giving foes wide, languid births results in, wait-for-it, even more monotonous, paint-drying travel.
The foes do, however, break into two types, ones that fires cannon blasts and the other being monsters that simply charge at you. Both of these types can be easily defeated by simply getting right behind them and staying there, shooting and shooting and shooting and... well, you get the point.
Some may describe this sticking to the rear of foes as strategy, but this works with just about everything, is boring and feels like an exploit. However, when stuck with limited resources (food and fuel) and poor weapons, this may be the only choice available.
I really wanted to like Sunless Sea. I hung in because I liked the imaginatively written stories, the murky graphics and the moody sounds, but the molasses slow travel and the totally broken combat forced me to abandon ship. Maybe if this game had spent a little more time in drydock, having it's combat system scrapped altogether or entirely rebuilt and travel sped up above senior citizen meandering, then I'd probably be playing the thing rather than writing this disappointed review.