Core gameplay is one of the more developed third-person shooters with a good amount of depth
This is a deeply incompetent and incomplete description.
To begin with, you can finish almost the entire game (possibly 100% of the game; it's been a while since I've played) without firing a shot, and still have plenty of options in so doing. This includes the intro sequence and both confrontations with Quiet (the sniper sidekick, for the uninitiated). You can also finish most of the game without being shot at, or even seen. Kojima calls it tactical espionage action for a reason, and it absolutely deserves to be called that, because firearms and weapons are in many way secondary or even tertiary to the core game.
It's not "one of the more developed" third-person perspective games, either. It's by far THE most developed. Snake has an incredible array of contextually and environmentally sensitive actions at his disposal, many of which can be combined in unique and unexpected ways. Just in terms of movement and positioning alone, he can stand, kneel, go prone, flatten out, and (in the prior three stances) move slowly, move quickly, roll left or right, kick over on his back and aim down toward his feet, or dodge in any direction; leg-sweep or tackle an enemy while crouched or prone; use cover from nearly any stance, and yank an enemy over or around an obstacle, or into concealment....
That barely even scratches the surface. Anyway, it's pretty great, best commando simulator of all time, and everyone should play it.
