This idea was originally meant for my educational online store, a One Button Game to teach about colors. In the end, I picked other video game ideas for this topic and did not use it.
The idea is that all players are graffiti artists. You have a specific color (“specialty”) and pressing your button makes you spray that color onto the wall.
Walls show (randomly generated) “paintings”, which are just some random shapes in random colors. Like, for example, a faded painting where the left half is entirely red and the right half entirely green.
Now the goal is quite simple and expected:
Spray the wall with the right colors
You win if you’ve covered the entire map/level with the right graffiti before time runs out.