Proof Game in 4 moves

Drat. The intentions were caveatcanis's answer for the 2nd, and the 2. Bf4 for the 3rd. I knew it was hard to compose, but not this hard. Well solved/cooked!

So here's another bunch!

A fix for the 2nd?

A change to the third.

Another try.

And yet another.

Answers in white (except the first one):

1. d4 c6 2. Bf4 Qc7 3. Bxc7 Na6 4. Bb8 Nxb8

1. e3 b5 2. Bxb5 Nc6 3. Bxc6 Rb8 4. Ba8 Rxa8

1. e3 d6 2. Bc4 Kd7 3. Bxf7 d5 4. Be8+ Kxe8

Homebase PGs in 4.0 have been posted in a link somewhere earlier. If your PG is homebase and 4.0, it's not the first.

My attempt:

Another one:

EDIT: Late.

Why not unique? No one else on this forum posted this puzzle. Even if there are multiple solutions, you can still try it. 

Plus, I don't understand what you mean by 'the move order for e2-e3-e4 and Ng1-f3xe5 are not determined.'  Nothing needs to be determined because that's what makes a puzzle a puzzle.

By the way, this was my firt attempt in trying. You could have at least complimented it.

You are new, so you do not know that it is quite possible to make proof games with a forced move order. People have been doing it that way for decades now. Experienced PG solvers expect this. Problems that don't have this are considered 'unsound'.

Okay, sorry if I sounded harsh there.

Basically what BigDogg stated. In "sound" (or correct) proof games, there is usually only one solution. (There are exceptions, but even then the solutions are usually related.) Different move orders, or even different ways to reach the same square, are frowned upon, making the proof game unsound (or cooked). Here are some of the solutions for your problem in post #78, which explains why it's unsound:

You can try most of the problems here, and they usually have a single solution; even the move orders or how to reach a particular square is fixed. An example of an unsound proof game here is post #80; if you try solving it, you will find that move 3 can be either 3. e4 dxe3ep or 3. e3 dxe3, making it cooked because these are variations that don't add beauty to the problem.

As for the new problem, sadly it's still cooked: 1. g3 and 2. Nh3 can be interchanged. But it's getting better; keep trying!

Oops! After thinking that the puzzle only has one solution, I should stand corrected. I wonder how many people are going to insult it!

I apologize for misunderstanding the word 'unique.' I thought you meant that someone else "used" it and I copied it. 

Thanks for guiding me in the correct direction.

Anyways, I will try again(and I will not give up):

Even though it may be simplistic, I think it is unique

@ chaotic_iak 

Yes, I was able to complete it in 3.5 moves:

When I tried again, I saw some solutions. Here's how I solved it:

Hopefully the excerise I did here improves my understanding about shortest proof games and general proof games.

Ok, here's my try:

After staring at that puzzle forever, I finally figured out the solution. It is brilliant!

#100 - Looks sound. And interesting too.

The one GreenCastleBlock posted is possibly the most famous (?) and trickiest (??) PG 4.0 there is out there. I've seen it used in almost every collection of short PGs, articles and even in normal chess lessons as a side activity.

One more try: