Pietnastka WORKING

#include <Windows.h>
#include <cstdlib>
#include <cstdio>
#include <ctime>
#include <cmath>

#define WND_WIDTH 1000
#define WND_HEIGHT 800

#define FIELDS 4

#define BTN_SIZE 60
#define GAME_START_X 20
#define GAME_START_Y 20

struct field {
    HWND Button;
    int Value;
    int PosX, PosY;
    int Width, Height;
};

HWND hwnd ,MovesInfo;
HINSTANCE hInstance;
field Field[(FIELDS*FIELDS)];
int NumberOfMoves = 0;

void DrawGameField(int i) {
    char buff[255];
    DestroyWindow(Field[i].Button);
    sprintf_s(buff, "%d", Field[i].Value);
    Field[i] = {
        CreateWindowEx(NULL, "Button", ((Field[i].Value != 0) ? TEXT(buff) : TEXT("")), WS_CHILD | WS_VISIBLE,Field[i].PosX , Field[i].PosY, BTN_SIZE, BTN_SIZE, hwnd, (HMENU)(Field[i].Value), hInstance, NULL),
        Field[i].Value,Field[i].PosX , Field[i].PosY,BTN_SIZE,BTN_SIZE
    };
}

bool IsInArray(int Value) {
    for (int i = 0; i < ((FIELDS*FIELDS)); i++) {
        if (Field[i].Value == Value) return true;
    }
    return false;
}

void InitGame() {
    int PositionX = GAME_START_X, PositionY = GAME_START_Y;
    int NewValue;

    for (int i = 0; i < ((FIELDS*FIELDS) - 1);) {
        NewValue = (rand() % (FIELDS*FIELDS));

        if (!IsInArray(NewValue)) {
            Field[i].Value = NewValue;
            Field[i].PosX = PositionX;
            Field[i].PosY = PositionY;

            DrawGameField(i);

            if (PositionX == (GAME_START_X + (BTN_SIZE * (FIELDS - 1)))) {
                PositionX = GAME_START_Y;
                PositionY += BTN_SIZE;
            }
            else {
                PositionX += BTN_SIZE;
            }

            i++;
        }
    }
    Field[(FIELDS*FIELDS) - 1].Value = 0;
    Field[(FIELDS*FIELDS) - 1].PosX = PositionX;
    Field[(FIELDS*FIELDS) - 1].PosY = PositionY;

    DrawGameField((FIELDS*FIELDS) - 1);
}

void MakeMove() {
    char buff[255];
    sprintf_s(buff, "Ruchy: %d", ++NumberOfMoves);
    SetWindowText(MovesInfo, buff);
    for (int i = 0; i < ((FIELDS*FIELDS)); i++) {
        DrawGameField(i);
    }
}

void SwapFields(field &F1, field &F2) {
    int FieldBuff = F1.Value;
    F1.Value = F2.Value;
    F2.Value = FieldBuff;
    MakeMove();
}

bool CheckWin() {
    if (Field[0].Value == 1) {
        for (int i = 0; i < (FIELDS*FIELDS) - 2; i++) {
            if (Field[i].Value + 1 != Field[i + 1].Value) return false;
        }
        if (MessageBox(NULL, TEXT("WIN"), TEXT("WIN"), MB_YESNO) == IDYES) {
            for (int i = 0; i < ((FIELDS*FIELDS)); i++) {
                Field[i].Value = (FIELDS*FIELDS) + 10;
            }
            MakeMove();
            InitGame();
        }
        return true;
    }
    return false;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    switch (msg) {
    case WM_COMMAND:
        for (int i = 0; i < (FIELDS*FIELDS); i++) {
            if (wParam == Field[i].Value) {

                if (Field[i].Value != 0) {
                    if (i - (FIELDS) >= 0 && Field[i - (FIELDS)].Value == 0) { // Pole nad puste
                        SwapFields(Field[i], Field[i - (FIELDS)]);
                    }
                    else if (i + (FIELDS) < (FIELDS*FIELDS) && Field[i + (FIELDS)].Value == 0) { // Pole pod puste
                        SwapFields(Field[i], Field[i + (FIELDS)]);
                    }
                    else if (i  % FIELDS != 0 && i - 1 >= 0 && Field[i - 1].Value == 0) { // Pole na lewo puste
                        SwapFields(Field[i], Field[i - 1]);
                    }
                    else if ((i + 1) % FIELDS != 0 && i + 1 < (FIELDS*FIELDS) && Field[i + 1].Value == 0) { // Pole na prawo puste
                        SwapFields(Field[i], Field[i + 1]);
                    }
                    break;
                }
                CheckWin();
            }
        }
        break;
    case WM_CLOSE: DestroyWindow(hwnd); break;
    case WM_DESTROY: PostQuitMessage(0); break;
    default: return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE HInstance, HINSTANCE hPrevInstance, LPSTR ilCmdLine, int nCmdShow) {
    srand(time(NULL));

    WNDCLASSEX window;
    MSG msg;
    TCHAR Class_Name[] = TEXT("OKNO_TEST"), Title[] = TEXT("Tytul");
    window.cbClsExtra = NULL;
    window.cbSize = sizeof(WNDCLASSEX);
    window.cbWndExtra = NULL;
    window.hbrBackground = (HBRUSH)(COLOR_WINDOW );
    window.hCursor = LoadCursor(NULL, IDC_ARROW);
    window.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    window.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    window.hInstance = hInstance;
    window.lpfnWndProc = WndProc;
    window.lpszClassName = Class_Name;
    window.lpszMenuName = 0;
    window.style = CS_VREDRAW | CS_HREDRAW;

    RegisterClassEx(&window);
    hInstance - HInstance;
    hwnd = CreateWindowEx(WS_EX_WINDOWEDGE, Class_Name, Title, WS_OVERLAPPEDWINDOW | WS_VISIBLE, CW_USEDEFAULT, CW_USEDEFAULT, WND_WIDTH, WND_HEIGHT, NULL, NULL, hInstance, NULL);

    InitGame();

    MovesInfo = CreateWindowEx(NULL, "STATIC", TEXT("Ruchy: 0"), WS_CHILD | WS_VISIBLE, GAME_START_X+(FIELDS*BTN_SIZE)+10, GAME_START_Y, 100, 50, hwnd, NULL, hInstance, NULL);

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    UnregisterClass(Class_Name, hInstance);
    return (int)msg.wParam;
}