Your choices throughout the game determine which ideological Reason you side with. It's possible for you lean toward Chaos with the demons, Law with the angels, the Neutral alignment that rejects Law and Chaos, and a few others that branch off from these. Characters who were once antagonists can become your allies, or vice-versa, depending on which path you follow. The world shapes itself in drastic ways through your choices, and rewards you with unique endings and special boss fights depending on your Reason.

The battles in the Shin Megami Tensei series are unforgiving in how difficult they are, and SMT Nocturne is among the hardest. You fight with a party of demons you collect, aiming to pinpoint your enemy's elemental weaknesses and exploit them. Once you find the weakness, you're rewarded with an extra turn; if you keep landing the right attacks, then the game lets you chain a finite number of turns one after another. If you don't look up a guide, then finding weaknesses is a matter of trial and error, and hoping you don't die while you figure things out.

But this also applies to your enemies -- if they exploit your weaknesses, then they get extra turns instead. Most of the opponents you come across hit for a ton of damage, so you absolutely need to take advantage of gaining extra turns. And as you get farther along in the game, you get access to buffs to your party's attack, defense, evasion, and more, as well as debuffs to debilitate your foes. As you get better with the combat and earn some tough victories, the sense of satisfaction you get helps you to keep pushing forward.

The Shin Megami Tensei games are all about atmosphere, and Nocturne absolutely delivers on this. The sheer sense of weight and gravity to everything around you, from the oppressive feeling in the air, to the hazy filter giving the world a distinct sense of personality, is really something else. And the soundtrack reinforces all of this, with hard-hitting rock and synthwave tracks that transport you to Nocturne's dark and demonic world.

The music embodies the ideologies that the game explores, giving you a majestic sense of religiosity for the law and order segments, and then turning around with menacing, experimental sounds to represent the demons and chaos. Everything goes perfectly together, keeping you on-edge as you explore the world and fight through the game's tense battles.

Demons and angels act as your party members in battle. While fighting, you can recruit almost any enemy demon or angel as long as it's at your level or below, through a process called demon negotiation. You barter with them through a conversation before asking it to join you; if it likes you, and if you give it the items, money, and whatever else it asks you for, it may join your party. You can then fuse angels or demons together to create stronger allies with better abilities. And there are hundreds of different types of demons and angels with their own fitting designs and relevant mythological lore, ranging from familiar names like Shiva, Lilith, Valkyrie, Phoenix, Raphael, and many many more.

While there is a story in Shin Megami Tensei: Nocturne, the way it's told purposely leaves a lot up to your imagination. You start off as a normal high school student going to meet up with his friends and his teacher, when the world suddenly ends and you're one of the few survivors left. You turn into a demon with glowing tattoos on your body, with the power to summon and control other demons in battle as your party members. Exploring the world and fighting through tough encounters rewards you with brief cutscenes where you learn about the ideologies of key characters in the game.

As you defeat powerful bosses, the world changes over time, opening up new areas to explore with even stronger enemies to take down. You spend most of the game wandering the world in search of power, treasures, and more demons to collect, with the gameplay and atmosphere as the focus while the actual story takes a back seat.