Thanks Eric and Airman. Much appreciated.
Here´s another relevant bump, showcasing a project with this situation:
The Client needed ideas for Games (in this case, mini-games for their little game Engine).
I offered some Game Concepts (characters and such); after approval I picked up the chosen ones and started to create the sprite work. The background for this games were created inside the Engine (My Doodle Game), using the built-in tools.
Since I don´t know who owns the Game IP nowadays, I don´t have a link for it. But a quick youtube search for 'My Doodle Game' will return some videos of it.
That´s it.
Any question, feel free to contact me:
contactdado -at- gmail.com. I´ll more than glad to help.