I've been working on my Advanced Wars clone for a while now, and so I've researched this a little bit. Game mechanics almost basically can't be copyrighted. It also helps (in my case) that I'm not really cloning 1:1 as much as I'm making a substantially different game in many key ways. Also I'm not using a sprite sheet found online, I'm making all my art assets myself at slightly higher resolutions. Mostly you should worry about:
using assets (art, sound, other files) you don't have the rights to.
I've been working on my Advanced Wars clone for a while now, and so I've researched this a little bit. Game mechanics almost basically can't be copyrighted. It also helps (in my case) that I'm not really cloning 1:1 as much as I'm making a substantially different game in many key ways. Also I'm not using a sprite sheet found online, I'm making all my art assets myself at slightly higher resolutions. Mostly you should worry about: