Shin Megami Tensei: Strange Journey was created to be somewhat of a throwback to the SNES-era Shin Megami Tensei titles. As such, the basic game engine is significantly different from its predecessor, Shin Megami Tensei: Nocturne. The game is a first-person dungeon crawler, more akin to Wizardy or Etrian Odyssey (upon whose engine Strange Journey was built) than to the third-person view of Nocturne.
The Demonica
Short for DEMOuntable Next Integrated Capacity Armor, the Demonica is a harsh-environment suit which uses adaptive technology to learn from the user's fighting style and increase his abilities. It protects the user and enhances his strength, speed, and durability. In short, the Demonica is the reason the investigation team can survive even a short time in the harsh environment of the Schwarzwelt.
The Red Sprite
The Red Sprite is the player's base of operations throughout the whole of Strange Journey. It serves as a sort of "town" in the conventional RPG sense; the player recovers health, buys equipment, and receives missions and sidequests here. It is navigated through a menu, listing the important locations on the ship; the command room, where senior officers gather to discuss the mission and issue objectives; the sickbay, where the player can pay Macca (the game's currency) to recover HP, SP, and remove status ailments; the lab, where scientists use "forma" obtained from demons to create equipment for the player; and the deck, from where the player embarks on the various missions issued to him by Commander Gore or Arthur.
Command Room
The headquarters of the Schwarzwelt Investigation Team. Commander Gore and Arthur spend their time here. Most of the main story missions will be issued from here, and there are several NPCs to talk to. You can also view your Mission Log, save your game, or load from either of the game's two save slots from here.
Lab
Irving and Chen head up the science team of the Red Sprite. Here, you can exchange Macca and some of the various forma you obtain during the course of your exploration of the Schwarzwelt for items, weapons, armor, accessories, and Sub-Apps (programs for your Demonica which provide small benefits). You can also trade in items and equipment you no longer need for a small amount of Macca (you don't get the forma you used to make them back, unfortunately). Items and equipment you have some, but not all, the forma required to create are displayed grayed-out, allowing you to check which forma you still need to acquire in order to make the item.
Sickbay
The medical team of the Red Sprite is housed here. For a small fee, you can heal some or all of your party, recovering HP, SP, and status ailments.
Deck
You depart here to the various sectors of the Schwarzwelt. Additionally, you can get a number of the game's sidequests here.