You did game design. that's cool!
I think your idea could totally work. although personally I'd like to see a more humorous take on social phobia in the game, because to me, games should always focus on the fun parts of real life. SP by itself is not very funny. Dealing with SP can be depressing but the game could make fun of it and perhaps make it interesting. hmm maybe you can do something like a Silent Hill world where the PC's SP makes him enter a hellish place where all NPCs turn into monsters that the PC has to avoid, and if he could calm himself down then he will be able to return to the normal everyday world. maybe the main plot of the game shouldn't even be about overcoming SP but overcoming SP would just be a side effect of completing the main quest. So that's my 2 cents.
I think whether you're choosing to make it RPG or adventure.. the main thing to worry about for now would be the storyline. I feel that a good story and good dialogues is the the main selling point for any adventure / RPG game. do you have a story in mind alredy? tell me more about it.
I agree with the humorous outtake, I was thinking most of it would be humorous in many ways. I was thinking more RPG at first since there then can be a level up system, for overcoming things, etc.
As for a story, I am lacking some there, I am still thinking on it, but I am thinking that as you said it wont be completely about SP, that is that with be an undercurrent, say for the main character, and will affect decisions he/she makes, and as the game goes that character overcomes it, etc.
Ok so for the humor, have you played over games like DOTT, Sam & Max, Monkey Island, Space Quest, etc. I realize all of these are adventure, and maybe a hybrid between rpg and adventure is still better. I say these though because they all take very humorous stances, and were quite fun to me. I would like these as an inspiration in humor.