Hi everyone!
Bit of a background and sort of an intro...
I've been working in the games industry for the last 30+ years or so my first EVER games console was a Philips G7000 (grew up in Holland). Started off in basic and then assembler on a vic20, I moved on with the whole industry. That said, I *love* constraints on hardware figured I'd see if I can create some games for the O2!
Anyway, the question I have is about Alien Invaders. If you look at the the image below:

I can kinda see a few possibilities in terms of sprite allocation:
- The spider (obviously) is 2 sprites. The bunkers are filled grid and the scores are most likely (up to) two digits using the four of the twelve 'fixed' sprites. The 4 quad texts can be used for the men and the circles below it... The bullets are then likely the remaining two sprites, doubled.
So the obvious question then is: How the hell are the shields under the men done and the bullets? Looking at the character set the shields are most likely done using the 'tree' with the two top lines color changed to blue but I'm curious to see if anyone has another theory!
-Mux