it's not possible otherwise people wouldn't be playing chess
King Citadel
Take this tic-tac-toe fantasy one step further. Suppose someone perfected such an opening, and it could not be refuted. The chessplayer would never lose/win a game, but drawing the top grandmasters would give him a high ELO rating even if he never won a game!?
It would be fun to try to create such an impenetrable fortress. Like all the sieges of history from Troy to The Cold War. As a B rated chessplayer, and no great military strategist, I appreciate anyone's sagecomment concerning my quest.
Is "play the hippo" just a glib remark, or is it a sincere hint towards realizing my heartfelt inquiry?! Explain yourself, hippo............
Although this is not the King Citadel I've imagined, how does the hippo ward off a strong attack for white, especially when 3 minor pieces are sitting on the queen's side?
It is not an impregnable fortress as such. I'd compare it to a fort with pots of boiling oil on the walls, a minefield around it and many angry soldiers hiding inside waiting to strike.
It wards of attacks by playing the right moves in the right order while preparing to strike back. If you just sit around or blindly play to reach the setup you WILL be crushed. (So not your ideal Citadel.) But it's strength is flexibility; the moves to get to the setup, as well as the following moves can all be tailored to respond to your opponent. Concretely, black usually has at least 3 of the ...c5/d5/e5/f5 pawn breaks available, and also ideas of ...g5-Ng6 or ...b5-b4, all of which will be threatened/executed as necessary depending on white's moves. Which of course is hard to put in practice.
Thank you for your insight hippo enthusiasts. However, I was thinking like a "bunker" with two ply defense of pawns and pieces surrounding the king. Supposedly the attrition of attacking pieces (keep pealing that artichoke...still more artichoke to peal) would leave us with no man standing results.
......or where chess becomes a 2D rubik's cube. Learn the combinations and you can draw everygame in 7 seconds! lol.
.....but not to worry. Obviously there are as many refutations to my supposition, because so many holes in it?! Or are there?

Since childhood I always wondered whether it were possible to create a purely defensive opening, which the opponent could not penetrate. Naturally this would result in a draw, but if the attacker makes a wrong move the counterattack would be devastating. It would appear as a King Citadel, which would mean no possibility of smothered mate, or any imbalance of material, space, or time. Has anyone proof one way or the other of this possibility, or any opening that simulates these conditions?