I remember trying - or at least thinking about - writing a few games inspired by the "Alien" / "Aliens" movies.
The only one that ever came to be, was inspired in one of the final sequences from "Aliens", when Ripley goes to rescue Newt from the aliens.
In this game, you are Ripley, trying to rescue Newt in the maze-like base, while avoiding the roaming aliens, before time runs out.
After reaching Newt, you have to go back to the starting point. Then in the next level, there will one more alien. If you got to 4 aliens, the next level will have just 2, but more aggressive ones.

In the original version, I used one of the two graphic pages (256x192x2) to store the map. In each loop, it would be copied to the 2nd page (the one being displayed), and the "sprites" would be drawn on. This saved a lot of time, since there was no need to "erase" the sprites, but caused a lot of flicker.
For the Remix, everything is drawn off-screen, avoiding the flicker, but forcing me to erase the sprites. With improvements and clean up of the code, the speed ended up about the same, some 6 FPS.
I also changed the colorset, from black and white to black and green (the only two options in the 256x192 mode), and re-centered the text, which is still in Spanish.
The final changes were a small redesign to the maze, to avoid some dead ends in which the aliens tended to get stuck, and limit the positions where Newt would be at the start of the level, so she wouldn't be either too close or too far.

If you want to read a bit more about this game, here are some blog entries about the remix.

The screenshots below show the original and remixed version, and the video cuts from one to the other.

You can download a .DSK file with the original and Remixed version of this and other games.