What should I do to distinguish an item which has the same color with its background?

Question

I'm making a game where some discs/circles moves around in a tiled map.

Each disc/tile have a color, and sometime the color of the disc and the tile are identical.

It would be hard for the user to know there's a disc lying on that tile, so I'm thinking of a way to make the disc reasonably visible. So far I've thought of 3 ways:

1. Darken/lighten the disc
2. Give the disc a dark outline
3. Give the disc a shadow

This is how I'm doing it currently, a combination of No.1 & 2.

But I'm not satisfied with it. Method 1 make it hard to recognize the true color of the disc when I have 8 or 9 different colors in the game. And method 2 and 3 both feel old.

So does anybody have experience with this and can help me out? How would you solve this problem?

Answer 1

I second the opinion above. In addition I would actually create the scenario in a graphics program (Photoshop, Illustrator, GIMP, MS Paint, etc.) to see what each would look like. In my personal opinion, I would recommend keeping the color and just adding the stroke and small drop shadow (Combination of 2 & 3).

Answer 2

Like you suggested, I will go with a border and a shadow (outer glow). As long as it can solve the problem, I will be fine with it!

Answer 3

My choice would be to ensure the disc color and the tile color never match.

All discs are 20% darker or 20% lighter than all tiles, etc.