For various reasons, the entire world is wrapped in an RPG system, but it's also entirely possible to exist outside the system, with both ups and downs. For example, poison created in the system is actually... just regular water outside the system. But physics and chemistry still exist in the world: At one point, one character fights another by blocking the system, using an robot and flooding the room with CO2. Blocking the system prevents the system from taking effect outside of their body (no magic and only internal buffs are possible, basically), robots are, well, like the Terminator in strength, and CO2 means that the victim will basically have to constantly focus on regenerating themselves internally.