diff --git a/README.md b/README.md
index 66bba51..8de8a33 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,5 @@
 # np-tetris
 
-tetris in numpy
\ No newline at end of file
+tetris in numpy
+
+Copyright 2024 Michael Pilosov, PhD
diff --git a/main.py b/main.py
new file mode 100644
index 0000000..6458aca
--- /dev/null
+++ b/main.py
@@ -0,0 +1,131 @@
+import numpy as np
+
+PIECES = {
+    "O": np.array([[1, 1], [1, 1]]),  # 2x2 block
+    "I": np.array([[1, 1, 1, 1]]),  # 4x1 horizontal bar
+    "L": np.array([[1, 0], [1, 0], [1, 1]]),  # L-shaped
+}
+
+
+def check_placement(piece, board, i, j):
+    n, m = piece.shape
+    if i + n > board.shape[0] or j + m > board.shape[1]:
+        return False  # Out of bounds
+
+    # Check for overlap
+    for x in range(n):
+        for y in range(m):
+            if piece[x, y] == 1 and board[i + x, j + y] == 1:
+                return False
+    return True
+
+
+def place_piece(piece, board, i, j):
+    board[i : i + piece.shape[0], j : j + piece.shape[1]] += piece
+    return board
+
+
+def attempt_rotate(piece, board, i, j):
+    rotated_piece = np.rot90(piece)
+    if check_placement(rotated_piece, board, i, j):
+        return rotated_piece
+    return piece
+
+
+def clear_rows(board):
+    clear_indices = np.where(np.all(board == 1, axis=1))[0]
+    if clear_indices.size > 0:
+        board = np.delete(board, clear_indices, axis=0)
+        new_rows = np.zeros((len(clear_indices), board.shape[1]))
+        board = np.vstack([new_rows, board])
+    return board
+
+
+def calculate_shadow(piece, board, i, j):
+    """Calculate the shadow (landing) position for the current piece."""
+    while check_placement(piece, board, i + 1, j):
+        i += 1
+    return i
+
+
+def display_board(board, piece, i, j):
+    display = board.copy()
+    shadow_i = calculate_shadow(piece, board, i, j)
+    n, m = piece.shape
+    # Overlay shadow
+    for x in range(n):
+        for y in range(m):
+            if piece[x, y] == 1:
+                display[shadow_i + x, j + y] = 2  # Shadow with different marker
+
+    # Overlay piece
+    for x in range(n):
+        for y in range(m):
+            if piece[x, y] == 1:
+                display[i + x, j + y] = 1
+    print(
+        "\n".join(
+            "".join("#" if x == 1 else "." if x == 0 else "*" for x in row)
+            for row in display
+        )
+    )
+    print()
+
+
+def main():
+    board = np.zeros((20, 10), dtype=int)
+    piece_types = list(PIECES.keys())
+    current_piece = PIECES[np.random.choice(piece_types)]
+    START_POS = (0, 4)  # Starting position
+    i, j = START_POS
+    auto_gravity = True  # Auto-gravity enabled by default
+
+    while True:
+        display_board(board, current_piece, i, j)
+        command = input(
+            "Enter command (a=left, d=right, s=down, w=rotate, S=drop, G=toggle gravity, Q=quit): "
+        )
+        if command == "Q":
+            break
+
+        if command == "a" and j > 0 and check_placement(current_piece, board, i, j - 1):
+            j -= 1
+        elif (
+            command == "d"
+            and j + current_piece.shape[1] < board.shape[1]
+            and check_placement(current_piece, board, i, j + 1)
+        ):
+            j += 1
+        elif command == "w":
+            new_piece = attempt_rotate(current_piece, board, i, j)
+            if check_placement(new_piece, board, i, j):
+                current_piece = new_piece
+        elif command == "s":
+            if check_placement(current_piece, board, i + 1, j):
+                i += 1
+            else:
+                board = place_piece(current_piece, board, i, j)
+                board = clear_rows(board)
+                current_piece = PIECES[np.random.choice(piece_types)]
+                i, j = 0, 4
+        elif command == "S":
+            i = calculate_shadow(current_piece, board, i, j)
+            board = place_piece(current_piece, board, i, j)
+            board = clear_rows(board)
+            current_piece = PIECES[np.random.choice(piece_types)]
+            i, j = START_POS
+        elif command == "G":
+            auto_gravity = not auto_gravity
+
+        if auto_gravity:
+            if check_placement(current_piece, board, i + 1, j):
+                i += 1
+            else:
+                board = place_piece(current_piece, board, i, j)
+                board = clear_rows(board)
+                current_piece = PIECES[np.random.choice(piece_types)]
+                i, j = START_POS
+
+
+if __name__ == "__main__":
+    main()