Exact Proof Game 2

Here's another exact proof game...and one considerably shorter than my last one.

An "exact proof game" is a type of retrograde chess problem in which the solver attempts to completely reconstruct, move by move, the history of the game.

Here's the position.  From this position, and the stipulation that it has been reached in a regular game of chess in 4.0 moves, the challenge is to completely reconstruct the game's move history.  ("4.0 moves" means that the position shown is immediately after black's 4th move.)  Good luck.

Please feel free to add comments as you make progress toward a solution, so that the collection of insights into this problem grows.

Note:  I did not compose this problem.  I will reveal the author when it is solved.

Amy

1.Nf3 e5 2.Nxe5 Ne7 3.Nxd7 Nec6 4.Nxb8 Nxb8

I agree with Crazychessplaya. The hardest bit was the swapping of black's knights- however, this seemed fairly obvious due to the fact the problem would be too simple in any other circumstance.

The way I came to this conclusion: Black is missing 3 pieces. Therefore, white's knight is going to have to capture a piece on every move but it's first. The only way it can do this at first is with 1... e5. The second thing I noticed was that black would have to capture white's knight on the 8th rank, to fit within four moves. The only way this could be possible, with black having to lose a knight on the fourth move, was the travelling of the g8 knight to b8.

Correct.  The composer is Andrei Frolkin after a problem by Ernest Clement Mortimer published in Shortest Proof Games, 1991

You can play out the solution here: