Well....It's different... LOL... I will start by saying that I have probably put ten hours into the game and I have only had it for three days, SO it must have something. But it's not like any other game theres no pace no thought of getting attacked, shot, blown up, or (sadly in my opinon) no worry of even getting the bends. so it's not a typical game. but with that said it seems vast and covers alot of species we keep in our tanks and many many more, you can choose to do assignments like be a diving guide or getting pictures for the local paper or you can go salvaging for items, all of these things may or may not progress the game, depending on how well you do them. it also runs through the seasons and only some fish can be seen in certain seasons, places or time of day. But the biggest thing is the music and atmosphere it really tends to pull you into the game (though it may be easy for me since a have over a hundred inch tv)
the only downside is that the interaction with fish gets a little repetitive it's one of the same 6 motions for any interaction to learn about them.
But all in all I think it has been amazing game.