This game may be tough. Even leaving aside any reservations I may have about its basic concept, it is simply not a very well made game.
When I first started playing, I didn't really notice. Chalk it up to my unfamiliarity with ships. My thought, when I noticed the Rainbow Warrior's snail-like movement speed was, "oh, of course, sea travel takes a long time - boy, they're hammering this 'realism' thing pretty hard." It was only when I tabbed out of the program and saw that Steam had my total play time at almost double my mission counter that I realized what was going on - the game was running at an abnormally slow rate.
I timed it with my watch. For every 30 seconds that passed in real time, 16-18 seconds passed in the game. It may have something to do with my computer (it was a top-of-the-line laptop . . . in 2011), but honestly, I don't think so. I just got done playing Skyrim, and while my machine was not quite powerful enough to handle it, I never experienced anything like this. Of course, it's possible that Ship Simulator Extremes is a greater graphical challenge than Skyrim, and I'm simply not tech-savvy enough to realize it (sure, Skyrim had complex terrain and foliage and hundreds of characters moving around a virtual world filled with various moveable items, and Ship Simulator Extremes, with its large expanses of open ocean looks a lot simpler, but I can't know how much physics simulation is going on under the hood - it could be that water far in the distance is being modeled just like the stuff under my boat, which I can imagine is a huge resource hog).
Anyway, I was able to mitigate that problem by turning down the graphics settings, though there is still a noticeable stutter to my ship's movement. And that's not the only technical flaw I noticed. During the first mission, thanks to my poor steering ability, I managed to ram the Rainbow Warrior's deployable speedboat into a massive, toxic-waste chucking cargo ship, and the bigger boat rose out of the water and proceeded to bounce up and down for the rest of the mission, as if it had become a massive, nautical lowrider.
Which is kind of a shame, because there are parts of this game that look really interesting. The campaign modes require you to captain a cruise ship, a customs patrol, or Greenpeace's much storied Rainbow Warrior.
And now I confess an unexamined and unwarranted prejudice. I'd always considered simulator-type games to be a stodgy and old-fashioned genre, like someone decided to make an electronic version of a model train. Thus, to the extent that I considered their potential political leanings at all, I always thought of them as politically conservative. So, it came as a great surprise to me that this game portrayed Greenpeace so favorably.
Of course, if I'd put more than two seconds of thought into it, I'd have realized that I'm, politically speaking, somewhere to the left of Lenin, and I think model trains are pretty cool, and thus something as badass as Greenpeace's nautical eco-vigilantism would have a much lower bar to clear for proving its worth as a video game subject (seriously, your reward for clearing the first campaign mission is a documentary film clip about the Rainbow Warrior where the Greenpeace activists pilot inflatable rafts next to a huge ship and catch barrels of toxic waste as they are being dumped into the ocean). I may also be overestimating how controversial Greenpeace really is - after all, it's not like there's anyone who's pro using the ocean as a dumping ground for radioactive materials.
There's also two more campaigns whose purpose I don't really understand - the Core campaign and the Pilot campaign. The descriptions lead me to believe that these are specific jobs on a ship, rather than particular types of ship, but I am also absolutely certain that there are nuances of ship-geek jargon that I am failing to pick up on.
So, after two hours, my initial impression is that if I can overlook its technical flaws Ship Simulator Extremes has the potential to be a pretty interesting experience, but that its slow pace and lack of moment-to-moment action (brief periods of intense flailing as I inadvertently do donuts in a speedboat and try ineffectually to straighten myself out notwithstanding) mean that it will seem like a much longer game than it really is.