"A larger world where the pieces are coming from" is perhaps a little over-the-top for Tetris - I only see the block-box as a means to give the player some room for planning and thinking a step ahead.
Yeah, I guess that part's stretching it. :P What I mean to say is that it further connects the player to the game beyond what's physically perceivable.Re: RPGs, I'd disagree that plot is necessarily the source of immersion either... but maybe we're using different Immersions.
You're not disagreeing with me on that. Indeed, it's only one of many possible sources of immersion. You can definitely take it out completely and still end up with a very enjoyable RPG, especially some of those open-ended ones.