Gaagaagiins Megaten is all about building your team of monsters and overcoming labyrinthine dungeons. The story is systematically the same: the world is ending for some reason or another, and different factions of monsters, gods, mythical creatures, legendary figures etc. (collectively called “demons”) from different mythologies and cultures are arguing which shape and philosophy the next world should adopt, typically torn between the “chaos” side promoting free will and individuality (i.e. the strongest survives), and the “law” side promoting order and hierarchy for the good of the whole group (i.e. absolute fascism). There are usually additional camps / philosophies which act as additional endings but all of them are irremediably doomed to dystopia. There is no “good” ending per say, even (in some cases especially) if you try to pick no side. Your avatar is simply choosing a direction for the World Reborn and helping it come to fruition.
Your team is entirely comprised of your protagonist + demons. NPC (whether demon or human) are rare and typically proxies advocating for the different philosophies and alignments. There is no “social link” or whatever form of Tokimeki Memorial-style simulation which has recently made Persona popular. Your main social experience is negotiating with demons to join your team. You negotiate either by completing subquests (rarely) or by talking to demons in the middle of battle (mainly). Some monsters like to be flattered, others want gifts, others will respond well to a ruthless personality. Some games add further recruiting requirements such as a specific alignment for your protagonist, or already having another demon on your team.
Demons function a bit like the monsters in Pokémon, except they fight altogether like a typical RPG party, rather than one by one. Instead of evolving pocket monsters, you fuse demons in order to get better ones. Ever since the DS era, you can choose hereditary traits from the “parent” demons to improved the infused demons (it used to be random). To keep the game balanced, the player can only recruit or receive fused demons which are at a level equal or below their own protagonist’s level.
Typically the dungeons and battles are more complex than in Persona. Since the PS2 era, the battle system in SMT and Persona and other spin-offs is pretty much always a variation of the same Press Turn system invented for SMT3. Attack an enemy with their elemental weakness and it will reward you with additional actions during your turn (this applies to the CPU attacking your team as well). Compared to a typical Japanese RPG, there is a much stronger focus on buff and debuff in SMT, both in terms of usefulness and efficiency. Each episode brings a few variations and additional mechanics but the core remains the same.
New to SMT5 is that you now have large exploration areas between dungeons and “villages”, rather than a schematic world map, and demons roam freely and visibly on the field instead of semi-random battles (in SMT4, you could see anonymous silhouettes of the enemies before they engaged you in battle).
