ive been playing Cortex Command for sometime and the one thing it needs other than that long list of things is a Day and Night cycle.

Has been discussed before.
Fairly complicated for little to no benefit.

Heres a simple way it could done , just change the background layer where it has all the rocks and ect to a Nightime look , and then haave it cycle.

Simple description. Difficult implementation.
Sort of like saying nuclear fusion is easy. 'You just have to get the atoms really close to each other'

yes , Fusion is easy...for about 13 seconds then something always gose bad.