I don't know about
Space Invaders, but
Pac-Man on the 2600 used incredible hacks that were widely criticized, but essential to cramming the spirit of the game into that tiny cartridge and puny machine.
Essentially, the 2600 gives the programmer 2 sprites only. One sprite is dedicated to drawing the Pac-Man main character, while the other takes the role of all four ghosts. That's right, simultaneously 1 sprite for 4 distinct ghosts, wherever they are on the screen.
This singular sprite and the practice of "racing the beam" leads to a lot of flickering. I believe that the flickering is so severe that it impacts the collision detection, so that Pac-Man can slide right through a ghost in the right place and time.
I owned a copy, of course, and it was just so sad to compare it with its daddy in the arcade cabinet. However, once Ms. Pac-Man rolled around, they had learned a lot of lessons, and made that one a rousing technical success.
Essentially, the 2600 gives the programmer 2 sprites only. One sprite is dedicated to drawing the Pac-Man main character, while the other takes the role of all four ghosts. That's right, simultaneously 1 sprite for 4 distinct ghosts, wherever they are on the screen.
This singular sprite and the practice of "racing the beam" leads to a lot of flickering. I believe that the flickering is so severe that it impacts the collision detection, so that Pac-Man can slide right through a ghost in the right place and time.
I owned a copy, of course, and it was just so sad to compare it with its daddy in the arcade cabinet. However, once Ms. Pac-Man rolled around, they had learned a lot of lessons, and made that one a rousing technical success.