I was having a discussion of my Lunar Lander game with someone in the PiDP-1 Google Group, and they asked if my version had a McDonalds? I was a little confused so I did a bit of research. It turns out there was a 1973 version of Lunar Lander (called Moonlander)  for the DEC GT40 (in essence an all-in-one PDP-11 with a VT11 graphics system and a display) that featured a McDonalds as an Easter egg.  You had to "fly" to the right-most edge of the scrolling moon terrain to find the McDonalds (with golden arches).  If you inadvertently (or purposefully) crashed into the McDonalds the game displayed the following message:

Upon successfully landing near the McDonalds, an astronaut would debark the LEM, go into the restaurant, and order..

then walk back to the LEM, get in, and fly away. Hilarious. 

No, I did not immediately jump into my code and add a McDonalds. What caught my eye was the Moonlander LEM's exhaust. 

I thought it was a pretty funky "straw broom like" look that matched the overall vibe of the game.  Now obviously that version of Moonlander had way more pixels and horsepower available on the DEC GT40 to create that effect than I do on the PDP-1, but to me the animation signaled that something was definitely going on when the engine was firing.

I played around with the idea a bit and came up with a two pixel implementation that I'm pretty happy with.

Actually the video above masks the fact that the two pixels at the tip of the exhaust spike are randomly blinking. It's more pronounced on the actual screen. Worth part of an afternoon in IMHO.

I have updated the Files section with the latest source code.