A while back, I was going to talk about the design aspect of color a little more. Knowing how to get different colors is important, but knowing what colors your working towards is more important.
I'm going to relate everything in terms of my own game Cygnus, because I put a lot of effort into the color design. Well, the first level at least, which dictated the colors I would use in subsequent levels. The player ship for example...
...when it came time to decide the color for the player ship, I could have chosen any color in the world, obviously, but I knew I wanted the color to represent something; stand out and be unique. There have been a lot of games where the player's ship is of a boring color and I definitely didn't want that for Cygnus. Also, I wanted the player to be able to know where there ship was among all the other lines.
One day, Nick was playing Super Metroid for the first time and I noticed that the over all color of Samus's suit (bright yellow) was an 'almost' exact compliment of the color of the very first level, which was a cold blue.
These two colors came together to really visually give the impression that this area was cold, old and Samus didn't belong and was trudging through, really upsetting the place. Also it was very visually stunning.
I knew from that, that the player's color in Cygnus should be a compliment to whatever the first level was. Since I knew the first level was going to be some sort of dirt-ish planet. I chose a light brown that I liked. Which actually ended up affecting the choice for every other color in the game; because I got the player compliment color from this, and each world had to be visually different. Since everything in the game is drawn with just lines, being different meant having a unique color. (And animation, but that's a differant post.)
So the "compliment" for the brown that I chose was a mute blue.
Also, since Gravitar was a big influence on the look and play of the game, I wanted to have the spawner be the same colors and animation as the spawner on Gravitar. So that blew the nice color compliment but it's okay cause it gives the first level a cohesive prop, which maybe the second screen doesn't have.
Since walls kill you, I really didn't feel the need for enemies, but, for things that move and animate around a lot, I colored red to let the player know that they are more dangerous than a wall.
Top-Secret P.S. - I forgot to comment out a piece of code in Cygnus that let's you hit the 'F' key for brakes. It was a line I wrote very early on when I was testing the movement code. It also sets your fuel to exactly 10. So if your going for a high fuel score don't press it, cause' it will cause your fuel to reset.