The year is 19XX. A power hungry rouge nation has invaded its neighboring countries, placing the stability of the entire world in danger. In order to preserve the peace, a secret submarine fleet, chosen from the best and brightest of the world's navies has been formed. They are known as the Steel Divers.
Now that I've gotten 100% of the story out of the way, let's move on to other parts of the game. Controlling your submarine is a pleasant challenge. There are two levers, speed and depth. The Submarines react sluggishly enough to make this fun to manage. The two bigger subs also have control for the angle of the sub (the biggest having more control over this than the medium), adding another layer of control.
There are three submarines to choose from, a small, medium, and large ship. They might as well have called them "easy", "medium", and "hard", but instead they pretend that there are pros and cons to each, saying that the smaller subs have better maneuverability and the bigger subs have better firepower. While this is true, the game puts such an emphasis on finishing levels quickly and no emphasis on destroying enemies. That, coupled with the high rate that the torpedoes reload and the fact that the small sub has the ability to fire a torpedo straight upwards, the added firepower isn't much of a bonus. However, I did find myself picking the biggest sub, since it was the most fun for me to control. One thing I found weird was that there is no way to turn around. Even if the levels requires you to go back, you just have to drive the sub backwards.
The Visuals are kind of nice. The 3D pops nicely, and the backgrounds are pretty with a nice use of depth. There's one level with an undersea volcano that look particularly good. An annoying issue is that there are actually enemies further in the background than you are sometimes. They can shoot torpedoes at you, but your inferior torpedoes can only move along the X and Y axis. All you can do is run away. Best and brightest, my ass. In one of the later levels there are whales swimming slightly in the background. They cross into the foreground at some point, but it's impossible to tell when they cross the magical threshold, so you can steer clear or risk collision. Those whales don't give a shit.
The sound is average and the music is forgettable. There's some voicing such as "All ahead" when you move the throttle all the way to the maximum or "Surface" when you move the surface lever all the way up. Usually I was jamming the levers all the way to one side or the other, so they got annoying quickly.
The levels mostly consist of getting to point A to point B, avoiding enemy subs, mines, walls, and other obstacles. After playing through the tutorial, this was no issue for me. You have enough health to go barreling through without any concern. If you do find yourself short on health, just head up to the surface, air restores your health. Occasionally, there will be a weak puzzle (such as shooting a glowing red button with a torpedo to open an door) and a hint, in case you are retarded (your torpedoes are no match for this door) .
Three of the seven levels have boss fights. The first one is the best. You encounter an unidentified sea creature, and without being provoked, you proceed to shoot the shit out of it. Immediately upon starting a boss fight, text will pop up on the screen pointing out the weak spots of the bosses (or if they were feeling subtle, tell you where your shots will have no effect). Once the weak spot is immediately announced to you, it becomes a game of waiting until the boss moves to a position to where you can hit the weak spot, and then hitting it. This is where they could've made the added firepower matter, but having more torpedoes doesn't help very much, since there is cool down period after you hit the weak spot. The cool down time is slightly less than the torpedo reload time. If you ever run low on health you can surface and restore it during all three fights. The latter two have planes bombing you if you surface, but you still restore health faster than they take your health down, and can avoid them pretty easily if you're moving.
Between each level you get to play "Periscope Strike". You move the 3DS around 360 degrees and shoot ships down. This works great in an office chair, but if you're playing on the toilet you won't be able to hit the ships behind you. Upon sinking a ship, you are rewarded with a decal that you can put on your ship (not too much control here. Just pick one and it'll slap it on the center of your submarine). Collect a certain number of a specific decal, and it'll activate a bonus, such as taking less damage from enemy mines, increasing your torpedo reload speed, or increasing your dive/surface speed. After playing each mission three times, I only have enough for two bonuses.
Unfortunately, I didn't find anything other than controlling the ship all that fun. The levels were easy, and I didn't have any trouble with the bosses. The game really seems to depend on you wanting to beat your best times. Annoyingly, levels 6 and 7 are locked until you beat all the previous levels with all three subs. Since I went through with the biggest sub first, beating a level the second and third time was less of a challenge than going through the first time.
Your enjoyment of this game will depend on how much you enjoy speedrunning easy games. Having been required to play all the levels three times (except the last), I can say I've had more than enough of this game already. There are only seven levels. Those without bosses take less than five minutes and those with them take about ten (at my constant "full speed ahead" pace). I have no motivation to go back and try to beat my times, and I don't really feel that the bonuses decals provide are great enough to grind for them. There's also a multiplayer mode that I didn't really go over. It's sort of like battleship crossed with advance wars. I don't understand it totally, but it seems that the winner is determined by who stumbles across their opponents ships first (much like battleship).
Overall, I wouldn't recommend this game. Controlling the sub is fun, but there isn't a good game around it.