Steel Diver

A Two Point Five D side-scrolling submarine simulator from Nintendo for their 3DS. You pilot one of three subs (an adorable little compact sub that can fire torpedoes vertically, a medium-sized submarine which is Jack of All Stats, and a four-torpedo-tube heavy sub) through a variety of stages, dodging depth charges, naval mines, and enemy submarines along the way. A gyroscope-enabled periscope minigame and a multiplayer turn-based strategy mode round out the package.

The following tropes appear in this game:

 * Boring but Practical: Sure, the small sub only has one torpedo tube, no pitch wheel, and is painted a rather ugly color, but as it turns out being able to fire straight up comes in handy.
 * Hot Sub-On-Sub Action: Inevitable, really.
 * Two Point Five D: Only it's in stereoscopic 3D, which makes it... 2.75D?