after the break...
Basically it's a 7 part episodic game where you play each of the Mane 6 in the first six parts and then you switch between all of them for the final. Also because of the different personalities and skills of each of the Mane 6, solving puzzles will be different for each of them for example:
Applejack would have to find something to move large things while Twilight would just use magic and while Pinkie could talk to anypony about anything, Fluttershy will have problems trying to say some things.
The plot could be something like something has happened to Sweet Apple Acres and Applejack and her friends need to put together a fund raiser of some sort and each of them have big ideas for it so they split up and try to make them happen... but as this is an Adventure Game it wont be as easy they hope it will be.
Edit: I've been think about this a little more about this and I have this to add.
Each pony will have their own unique thing to help them work on their project and stop the disaster they accidentally make. Like Apple Jack will have her strength to help with tasks like breaking something or getting something down and so on. Fluttershy can get animal help which explains itself. Twilight can use her knowledge of magic for a wide range of tasks (as long as she's got the spell right) also Spike can help. I don't know what Rarity could do yet but she could have Spike's help instead of Twilight if I never do. Pinkie Pie will basically have the strangest possible solutions to her problem but not impossible to figure out to make her as fun as possible to match her personality (ponyality?). And Rainbow Dash is stuck with Derpy as an assistant as a favour for the first thing she needs.
Edit 2: Rarity could have charisma has her unique problem solving skill. Why? Well out of the six she seems to know how to talk others into giving her what she wants. This can come in handy in an adventure game but to stop things getting too easy I'll have to think of something.
If I could pull it off I would put more thought into it like what specific problem it could be, who they have to get help from, what ideas do the Mane 6 have and so on. It's a real shame how I keep coming up with ideas I have no chance of making but in the slim chance someone want to help make it I would be glad to work with them somehow. So if you know any talented people you think might be interested please let them see this post, I'm not confident enough to build a team myself. On an unrelated note, I've started writing a Fan Fiction and at the moment it's only got 1 chapter and will likely be like that for a while as it's my first time writing a story and I'm not very confident at it.
Edit 3: I've now got someone to do backgrounds/sprites and another person who offered to do the music. The only things missing are a full story (I could do) and someone who can use AGS (I tried, oh lord I tried).
Edit 4: New post!