This is a 'Hires' version of Space Invaders for the ZX81. It features pixel by pixel movement in both horizontal and vertical directions and a split display. 

Most of the screen is in 'hires' but it then flips back into 'lowres' for the bottom few lines to display the score, hiscore and lives. The "Hires/Lowres split screen" code has been tested as working on a real ZX81 with 16K RAM Pack

You can download the .p binary file here and the complete source and binary pack from here. The full project is also available on github. Invaders uses all the tools and techniques described in the previous pages to produce a complete hires game for the ZX81. 

You can play the game in the emulator above or see it in action on real hardware in this video

Source code of the main file (pacman.asm) listed here.