This is my own version of space invaders programmed completely in x86 assembly. Everything, including font and number rendering, is done by hand. High scores between sessions are saved to a file to keep track of progress.

The full source code can be found here.

The main loop of the game looks like the following:

 

Start PROC NEAR
	CALL Init
	CALL Initial_Title
	CALL Instructions
	CALL Level1			;Init level 1
Main_Loop:				;Main game loop
	CALL Draw_FPS			;Draw the FPS (frames per second)
	CALL Get_Ticks
	MOV START_TICKS,EAX		;Ticks with which we start
	CALL Draw_Score
	CALL Render			;Draw the entire scene
	CALL Collisions			;Check if there are any collisions
	MOV AH,01h			;DOS Function: Check for characters in buffer
	INT 16h
	JZ No_Char
IS_Char:
	MOV AH,00			;DOS Function: Obtain character from buffer into AL
	INT 16h
	CMP AL,'q'
	JE End
	CMP AL,'Q'
	JE End
	CMP AH,77
	JE RShip
	CMP AH,75
	JE LShip
	CMP AL,32
	JE Shot
	JMP No_Char
RShip:
	INC SHIP_X
	JMP No_Char
LShip:
	DEC SHIP_X
	JMP No_Char
Shot:
	CALL Create_Ship_Shot

No_Char:
	CALL Update_World		;Update everything that needs to move.
	CALL Check_Limits		;Bound the ship to the limits of the screen.
	CALL Win_Condition		;Check if all the space invaders have been eliminated.
	MOV DELAY_TICKS,1		;Wait 1 hundredth of a second.
	CALL Delay			;Waist CPU cycles to cap the FPS.
	CALL Get_Ticks
	MOV END_TICKS,EAX
	JMP Main_Loop
End:
	CALL Stop 
Start ENDP