Extra Credits explains how a ‘swift kick to the head’ with the Boot of Consequence jolts a player into treating the game world as a ‘real’ world and how Permanence reinforces that ‘real world’ environment so that the player starts to behave like a ‘real’ character in that world.
And I’ve got one thing to add to that. Design your game world so that it NEVER breaks the ‘fourth wall’!
That means that every element of your world has to make sense according to the rules you’ve established for that world. No leaps of logic. No Deus Ex Machina. No ‘because it’s a game’ stuff.
No-one should be forced to eat out of a trash can!