diff --git a/Makefile b/Makefile
index b10ac62..d8f070f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,15 +1,15 @@
-all: mbr.img
+all: tetros.img
 
-mbr.img: tetros.asm Makefile
-	nasm -d DEBUG -f bin tetros.asm -o mbr.img
-	@echo "size is" `stat -c "%s" mbr.img`
-	@if [ `stat -c "%s" mbr.img` -gt 446 ]; then \
+tetros.img: tetros.asm Makefile
+	nasm -d DEBUG -f bin tetros.asm -o tetros.img
+	@echo "size is" `stat -c "%s" tetros.img`
+	@if [ `stat -c "%s" tetros.img` -gt 446 ]; then \
 		bash -c 'echo -e "\e[91mOutput exceeded size of 446 bytes.\e[0m"'; \
-		rm -f mbr.img; exit 1; fi
-	nasm -f bin tetros.asm -o mbr.img
+		rm -f tetros.img; exit 1; fi
+	nasm -f bin tetros.asm -o tetros.img
 
 run:
-	@qemu-system-i386 -drive file=mbr.img,index=0,media=disk,format=raw
+	@qemu-system-i386 -drive file=tetros.img,index=0,media=disk,format=raw
 
 clean:
-	rm -f mbr.img
+	rm -f tetros.img
diff --git a/README.md b/README.md
index cc90f93..5fb7748 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,18 @@
 # TetrOS
 TetrOS is a small *feature rich* Tetris clone which is written in Assembly.
 It fits completely into a 512 byte boot sector and is executed during the
-boot sequence. It does not need any existing operating system. TetrOS is its own
-operating system, hence the suffix OS in its name.
+boot sequence before any operating system is loaded. It does not need any
+existing operating system. TetrOS is its own operating system, hence the suffix
+OS in its name.
 
 This is how it looks like:
 
 ![TetrOS - Tetris in 512 byte boot sector](https://github.com/daniel-e/mbr_tetris/blob/master/tetros_tetris_screenshot.png)
 
+And this is how the machine code looks:
+
+![TetrOS - Machine code](https://github.com/daniel-e/mbr_tetris/blob/master/code.png)
+
 ## Features
 * Each brick shape has a unique color.
 * Blinking cursor is not visible.
@@ -21,6 +26,11 @@ This is how it looks like:
 ## Features missing due to size limits
 * Scores and highscores.
 * Intro.
-* Game over message.
+* Game over message and restart without rebooting.
 * Show next brick.
 * Increase speed.
+
+## Similar projects
+* https://github.com/dbittman/bootris
+* https://github.com/Shikhin/tetranglix
+* http://olivier.poudade.free.fr/src/BootChess.asm
diff --git a/code.png b/code.png
new file mode 100644
index 0000000..ce20326
Binary files /dev/null and b/code.png differ
diff --git a/dev/additional_features.asm b/dev/additional_features.asm
new file mode 100644
index 0000000..fc2d595
--- /dev/null
+++ b/dev/additional_features.asm
@@ -0,0 +1,45 @@
+; game_over:
+; 	mov cx, 10
+; 	mov dx, 0x0323
+; 	mov bx, 0x8c
+; 	mov bp, game_over_msg + 0x7c00
+; 	mov ax, 0x1300
+; 	int 0x10
+; 	xor ax, ax                   ; wait for keyboard
+; 	int 16h
+; 	jmp start_tetris
+
+;game_over_msg: db "GAME OVER!"
+
+; ==============================================================================
+
+initial_animation:
+;	call clear_screen
+;	mov ah, 2                    ; set cursor position
+;	xor bx, bx
+;	mov dh, 5
+;	mov dl, 10
+;	int 0x10
+;	mov si, message + 0x7c00     ; MBR is loaded at address 0000:7C00
+initial_animation_next:
+;	cld
+;	lodsb
+;	cmp al, 0
+;	jne initial_animation_do
+;	xor ax, ax                   ; wait for keyboard
+;	int 16h
+;	ret
+initial_animation_do:
+;	mov bx, 0x0a                 ; write character
+;	mov cx, 1
+;	mov ah, 9
+;	int 0x10
+;	call cursor_right
+;	push dx
+;	mov cx, 2                    ; wait 2x65536 microseconds
+;	xor dx, dx
+;	call wait_abit
+;	pop dx
+;	jmp initial_animation_next
+
+;message:     db "Let's play tetris ...", 0
diff --git a/dev/bricks.txt b/dev/bricks.txt
new file mode 100644
index 0000000..832249e
--- /dev/null
+++ b/dev/bricks.txt
@@ -0,0 +1,152 @@
+.X..
+.X..
+.X..
+.X..
+
+XXXX
+....
+....
+....
+
+.X..
+.X..
+.X..
+.X..
+
+XXXX
+....
+....
+....
+
+====
+
+..X.
+..X.
+.XX.
+....
+
+XXX.
+..X.
+....
+....
+
+.XX.
+.X..
+.X..
+....
+
+X...
+XXX.
+....
+....
+
+====
+
+.X..
+.X..
+.XX.
+....
+
+..X.
+XXX.
+....
+....
+
+.XX.
+..X.
+..X.
+....
+
+XXX.
+X...
+....
+....
+
+====
+
+.XX.
+.XX.
+....
+....
+
+.XX.
+.XX.
+....
+....
+
+.XX.
+.XX.
+....
+....
+
+.XX.
+.XX.
+....
+....
+
+====
+
+XX..
+.XX.
+....
+....
+
+..X.
+.XX.
+.X..
+....
+
+XX..
+.XX.
+....
+....
+
+..X.
+.XX.
+.X..
+....
+
+====
+
+.X..
+XXX.
+....
+....
+
+.X..
+XX..
+.X..
+....
+
+XXX.
+.X..
+....
+....
+
+X...
+XX..
+X...
+....
+
+====
+
+.XX.
+XX..
+....
+....
+
+X...
+XX..
+.X..
+....
+
+.XX.
+XX..
+....
+....
+
+X...
+XX..
+.X..
+....
+
diff --git a/tetros.img b/tetros.img
new file mode 100644
index 0000000..d4572e5
Binary files /dev/null and b/tetros.img differ