Fast Leveling in Navy Mission
Get comfortable switching between the main gun, Phalanx, and missiles early -- since threats come from all directions, relying on just one weapon system is confirmed to leave you exposed to whichever threat type it doesn't handle well.
With four confirmed difficulty levels available, don't feel pressured to start on the hardest setting -- work through the 30+ missions at a level that lets you learn the main gun/Phalanx/missile switching rhythm comfortably first.
Once you're comfortable with the core mission structure, the endless survival stage is confirmed as a dedicated mode specifically for chasing a high score, separate from the story-style mission progression.
See the full data: Navy Mission Getting Started