The thing is, it is highly recommended that these sorts of room-structure thingies are visual... I mean, if I were presented with a menu that says "Go Up. Go Down. Go Left. Go Right." I would bang my head against the monitor in frustration.
Been thinking about this... I think I'll either go with the Nocturnal Illusion solution : a map of the current floor/zone, a simple click leading you to a room... or with a list of places you can go from where you are (you're in the lobby, you get an icon for the dining room, the hall and upstairs).
The first solution means the player could maybe "skip" places that should otherwise be physically gone through according to the map. This is a bit silly if the hall is linked to the dining room which is linked to the kitchen and... when going directly to the kitchen, you don't meet A, whom you meet when going in the dining room. Actually, maybe the player wouldn't really notice it (just thinking the person got there after he went to the kitchen)... mm... would have to test it out. But it sounds a bit "dangerous" at least
.
The second solution means it's a bit more annoying for the player since he actually clicks through places he doesn't need to be at. But it might also help with the immersion (I'm really there, I'm bound to logical rules of moving around), and *maybe* make the player remember about things he wouldn't otherwise (my goal is the kitchen, I go through the dining room and spot Mika whom I had to tell something to... let's do that).
I also thought about "clicking" the backgrounds but this would require proper bgs and could turn things into pixel hunting which I'm not fond of. A clear list of choices seems better.
** Interactions **
There are gradual ways to complexify these...
The simplest is that by simply being in a room where something is supposed to happen, it will happen. If raised a conversation flag for Mika, the next time Mika is in the room, you'll talk to her. Simple, but it would mean the player only "moves around"... A bit *too* simple and boring imo ^^;...
I would rather go with two other menus : characters and objects/actions. If a character is in the room, a thumbnail is clickable to interact with him. It doesn't mean the character won't initiate a convo at times, but most of the time, it's the player would should know who to talk to.
As for actions, they would probably be a simple text list. This gives much freedom : maybe usually the living room only has "rest" and "watch tv"... but if you raised the "light bulb pops" flag, then you would also get "fix the light".
It could be more complex, with a whole visible inventory, separate objects with multiple actions (look, use, take) but this would really turn into some first person view adventure game with, I think, too much complexicity for its own good.
In the end, this means that after each "move", you would get the "move to", "characters" and "actions" menus on the screen. It could be handled through regular Ren'Py menus but it could mean a list of 10 possible choices after each click ^^;... so a specific interface seems appropriate.
** Phases **
There's something I want to have to simplify things and avoid story-based bugs as much as possible : phases. I think they're called "scenes" or "acts" in the last Inform version. Basically, I'd define multiple time periods which globally define the state of the game (time of day, general ambience, where most people are, what can be done, what's the main goal) and have only a few "exits".
Until you find the exits (through talking, acting, etc...), you would stay in these little sandboxes. The good point is that I would know exactly what's possible during a scene. I wouldn't forget that "if you didn't do that right at the beginning, this character now appears in two places". This happened a lot in MagBou ^^;...
Phases means less freedom for the player, but a more secured environment in which to play. There would probably be things that can be done in multiple phases and things that are carried over from one phase to the other... giving a sense of continuity.
But overall, I would be able to draw a very simple diagram of the phases and have something similar to your run-of-the-mill VN with choices.