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What kind of 2D game do you need? A mario-style sidescroller? A classic RPG? Or arcade-style? Except for the second one, you'll need custom scripts, and so this belongs in script requests.
If you're trying to do something like that, you might be better off starting out with a program like Game Maker, instead of trying to redefine the basics of RMXP.
If you were asking for a 2D script, why would you want 3D features?
What you want is a platformer script, in which the player jumps on ledges and enemies and whatnot. I don't think one's been made for VX yet, but you can request it here. Although my suggestion is, like Glitchfinder said, just use a different program designed to make platform games, it's a lot easier.
You do realize RPG Maker VX is already 2D? X and Y axis, no Z. >_>;
I know this is on here, look in Submitted Scripts, I can't be bothered to find it right now.
I have seen it though, and it works pretty well, actually.