ZorbaTHut's answer is probably what you seek, but nevertheless I'd like to enhance it a bit.
Something that I sadly hear too much is that “it’s not illegal to copy someone’s style”. Sure, if you create an illustration that is completely derivative of someone else but not a direct rip-off or tracing, they might have a hard time suing you. That doesn’t make it OK to make derivative work.
What Jessica is trying to emphasize throughout her post is that there is a difference between being inspired by some art and trying to imitate/copy/trace it (tracing is the process of "following"/tracing the outline of some art, and then simply colouring it or at least changing it slightly).
As for what portions of a game can and cannot be protected:
- The concept of a game cannot be protected -- you can make as many games as you want about plumbers who smash things with their
- The code itself is protected by copyright, but you only violate copyright by duplicating said code -- in other words, you looked at
their code and replicated it, or used their code verbatim somehow.
- The code itself could conceivably contain algorithms that are patented, which would be protected -- If the algorithm is core to the
game in some way, you'd have to figure out an alternative
implementation that achieves the same thing, and it can't be a trivial
transformation of the original algorithm.
- Artistic elements -- graphics, sound, music, level design, etc -- are protected by copyright at a minimum. You can't replicate these things verbatim.
- Some artistic elements that are unique and highly recognizable are also protected by trademark -- trademark protects firms from
replicas that are meant to pass themselves off as the original -- You
can make graphics for a blue plumber that likes to jump on tortoises
just fine, but he better not have a mustache, be named "Nario", and
speak with an Italian accent. Trademark is essentially about
counterfeiting, its still a violation even when you change small
things if the purpose is to deceive customers, or otherwise mooch of
the good name of the authentic item.
I found some wonderful site on fangame copyright issues long ago that I couldn't find again right now, but the author's final advice would be something like this:
If you are in doubt whether what you've created is violating copyright, DON'T use it.
If you really have to (completely) copy art, characters or mechanics from another game, then your game isn't really worth publishing to the world. Bring in your own twist, invest in your game's design, create new and exciting characters, storyline and mechanics, even use "programmer's art" in order to express yourself!
Thus, why use dots and a yellow/blue/whatever sliced pizza as a character? Create a chipmunk collecting nuts, create a farmer collecting eggs while being hunted by angry chickens (lol), something different, something exciting! :)