This twist especially shines when you get to the chapters where the other games start to invade the world our protagonist has reincarnated into, where the "rules", conventions and styles of game play clash. The interesting ways both the nation Mynoghra and the various antagonists uses their "rules" in order to subvert the world's logic makes every fight tense and lends itself to clever solutions within the narrative. The alignment system as well make for interesting story telling, seeing the subtle ways, and sometimes not, the alignment changes how some characters act is interesting to see. There's a chapter later in vol 3 that really makes me excited for what the alignment system can do narrative wise.

Ideas that have never been used: NPC characters in other games are transferred to the world where MC is

The game system is also transferred. That is, when an RPG game character is transferred to a new world, the RPG system in the game will still bind the game character. For example, when you fight a boss in an RPG game, you will not be able to back down, the only choice is to defeat the boss or you die, now when in a new world, the system also participates in battles, whoever fights the boss of an RPG game will not be able to escape. The only choice is to beat the boss or die.