Ahhh... *flexes imagination muscles*. I apologize if I go into details too much, and constantly refer to the final fntasy series of games.
The game of my dreams would be an RPG that's sorta a cross between Chrono Cross (yes I know its an old game) and Final Fantasy 8. They're me 2 favourites.
Following the Squaresoft trends, the magic system of this RPG would be the crux of the game. It should utilize the elemental system from Chrono Cross and the junction system of FF8. That is, the player should be able to junction the six elemental magic to the characters, yet the characters should have at least one unique ability to maintain originality, unlike the character monotony of FF8. The summons spells would use some from both games.
As for character development, I recommend the Chrono Cross element. In CC characters have no levels to gauge them; instead thier stats grow bit by bit after very battle, say +2 in Dexterity and +1 in Strength or something after every battle. They should recieve considerably larger stat boosts after boos levels (duh) of say, +6 in Mag.Def, perhaps? I'm tired of levels gauging the character's strength...
Of course, CC has far too many characters to choose from (>35) hence players feel no emotional attachment to anyone. Hence I prefer as few playable characters as possible, like FF8. The travelling party should consist of only 3 characters during battle or exploration. They should follow the main character behind like CC.
As for weaponry, there isn't a problem since the upgrade system of FF* is rather similar to that of CC; you have to hunt for the raw materials yourself. The money system should be that of the standard CC; I did't really like the FF8 pay system.
To do the entire battle system, I really liked the Chrono Cross' unique style of stamina. Standard Final Fantasy Active-Time is too cliche. There has been situations where all characters simply sat there staring at each other. With CC, you are doing something all the time; the player hould not be allowed to rest (hehehe). Of course, there will be major alterations to the battle menus of this new game; "Battle, Magic, Summon, <ability>, Item". And oh, you should be able to pause the game ANYWHERE.
Saving is simple, keep the save points.
The storyline. The major part. Of course, no one wants a story that drags on forever. Keep it understandable to 15 year olds (I'm 16, but that should be the target audience). Try to include science, such as the time experiments and quantum phisical aspects of CC, and technology, such as rockets and hi-tech cities in FF8. Medieval bits are appreciated too, such as the use of swords (guns are so overused by futuristic games). It ould be set in a hi tech world with some slums and villages here and there, hi-tech swords and a cliche "mysterious force at work" theme, like that of CC and FF8.
The music... I want Yasunori Mitsuda, the musician of Chrono Cross to do the music. He was excellent with handling the music of CC. He was the only RPG OST musician I ever bothered to find out the name of.
As for the character design, I choose (uh, forgot the name... Must... Remember...) whoever did that for FF 7 and/or 8. CC would do as well. The graphics shouldn't be a problem, just make the best of the best.
A final note: The game should include "New Game +" and/or "Continue +"just like CC. And there should be plenty of splits in the storyline, where characters have to make choices, like CC and multiple endings as well. And of course, a bunch of secrets to unlock.
Well that's what I'd call my dream game.