user11071: Define an "elegant" checkmate as one in which

the king is not on the edge of the board
the king and each of the 8 squares surrounding it are each attacked by exactly one, different opponent piece. (In other words: 9 pieces each attack exactly one of those squares)
none of the squares touching the king are occupied by pieces of the king's colour

For instance, this is an elegant checkmate:
8/3B1N2/2K5/8/4k3/1N1P2P1/2P2PP1/8 w - - 0 1

Now, what is the shortest game that leads to an elegant checkmate?

user11144: I'm not very good at proofgames, but if I counted correctly, 12 move suffice:
[FEN "rnb3nr/pppp1Npp/4p3/8/4k3/1QP2PPB/PPP2PKP/RN5R w KQkq - 0 1"]

Moves are obvious: Black sacrifices B-b4-c3 and Q-xBg5-g4-f3 in that order, White plays Q-d5-b3. Last moves are 10.Nf7+ Ke4 11.Kg2 Qf3+ 12.exf3#. An retro expert will manage 11, at least :-)
Proof game:
[FEN ""]
1.Nf3 e6 2.Ne5 Bb4 3.g3 Bc3 4.dxc3 Ke7 5.Qd5 Kf6 6.Qb3 Kf5 7.Bg5 Qxg5 8.Bh3 Qg4 9.Kf1 Ke4 10.Nxf7 Qh5 {Black has one extra tempo to waste, at this point or before} 11.Kg2 Qf3 12.exf3#


user14079: I think this achieves the task in 15 plies (mate after White's 8th move):
[FEN ""]
1. b4 d6 2. a4 Bf5 3. Nf3 Bd3 4. Ba3 Kd7 5. Nc3 Kc6 6. Nd5 Kxd5 7. e4+ Kc4 8. cxd3#

The 9 white units necessary for mate are 5 pawns, 2 bishops, 1 knight and the queen.
In case you are bothered by the two Bishop+Pawn batteries (one might consider than c5 is attacked twice, by Pb4 and Ba3), then we need one more move:
[FEN ""]
1. Nc3 d5 2. Nb5 Kd7 3. e4 Kc6 4. Nxa7+ Kc5 5. Ke2 d4 6. a3 Kc4 7. b4 Nd7 8. Nf3 d3+ 9. cxd3#

Mate is delivered by 5 pawns, 2 knights, 1 king and 1 queen.

11071: <p>Define an &quot;elegant&quot; checkmate as one in which</p>
<ul>
<li>the king is not on the edge of the board</li>
<li>the king and each of the 8 squares surrounding it are each attacked by exactly one, different opponent piece. (In other words: 9 pieces each attack exactly one of those squares)</li>
<li>none of the squares touching the king are occupied by pieces of the king's colour</li>
</ul>
<p>For instance, this is an elegant checkmate:</p>
<pre><code>8/3B1N2/2K5/8/4k3/1N1P2P1/2P2PP1/8 w - - 0 1
</code></pre>
<p>Now, what is the shortest game that leads to an elegant checkmate?</p>
 11144: <p>I'm not very good at proofgames, but if I counted correctly, 12 move suffice:</p>
<pre><code>[FEN &quot;rnb3nr/pppp1Npp/4p3/8/4k3/1QP2PPB/PPP2PKP/RN5R w KQkq - 0 1&quot;]
</code></pre>
<p>Moves are obvious: Black sacrifices <code>B-b4-c3</code> and <code>Q-xBg5-g4-f3</code> in that order, White plays <code>Q-d5-b3</code>. Last moves are <code>10.Nf7+ Ke4 11.Kg2 Qf3+ 12.exf3#</code>. An retro expert will manage 11, at least :-)</p>
<p>Proof game:</p>
<pre><code>[FEN &quot;&quot;]
1.Nf3 e6 2.Ne5 Bb4 3.g3 Bc3 4.dxc3 Ke7 5.Qd5 Kf6 6.Qb3 Kf5 7.Bg5 Qxg5 8.Bh3 Qg4 9.Kf1 Ke4 10.Nxf7 Qh5 {Black has one extra tempo to waste, at this point or before} 11.Kg2 Qf3 12.exf3#
</code></pre>
 14079: <p>I think this achieves the task in 15 plies (mate after White's 8th move):</p>
<pre><code>[FEN &quot;&quot;]
1. b4 d6 2. a4 Bf5 3. Nf3 Bd3 4. Ba3 Kd7 5. Nc3 Kc6 6. Nd5 Kxd5 7. e4+ Kc4 8. cxd3#
</code></pre>
<p>The 9 white units necessary for mate are 5 pawns, 2 bishops, 1 knight and the queen.</p>
<p>In case you are bothered by the two Bishop+Pawn batteries (one might consider than c5 is attacked twice, by Pb4 and Ba3), then we need one more move:</p>
<pre><code>[FEN &quot;&quot;]
1. Nc3 d5 2. Nb5 Kd7 3. e4 Kc6 4. Nxa7+ Kc5 5. Ke2 d4 6. a3 Kc4 7. b4 Nd7 8. Nf3 d3+ 9. cxd3#
</code></pre>
<p>Mate is delivered by 5 pawns, 2 knights, 1 king and 1 queen.</p>
