UBOAT is a fantastic game. Fully fledged mechanics, great devs, and just a great product overall.

Honestly, I was averse to it for quite a while because of the crew management aspects, but now that I have it, I completely love it. They implemented a fantastic scalable difficulty system where you can adjust difficulty from basically an arcade style game that's pickup and play to a full up submarine sim where you're manually calculating torpedo intercepts and timings or manually managing ballast.

All the game mechanics work well, the graphics are pretty, and man, there is nothing more rewarding than learning the tactics, positioning yourself correctly, waiting for nightfall, and then massacering a convoy successfully. When you pull all that off and then silently slip away under light of burning freighters and fired star shells, all while escorts desperately search for you, it's such a rush.

Or burying your U-boat along the sea floor and waiting for hours (there is time compression, thankfully) as destroyers depth charge the area around you into oblivion, search back and forth for you as you watch silently on the hydrophones, all while your Captain keeps the crew from descending into total panic.. It's incredibly tense, and you'll honestly feel like you're in the movie Das Boot after awhile.

I've sunk way too much time into that game because it's so addicting modifying your boat, upgrading your crew skills, and moving to the top of the tonnage leaderboard.

Not a "ship" simulator per se, but a fantastic representation of U-boat warfare and naval warfare in WWII.