I am currently developing a platformer. The game engine itself is going to be past the alpha testing stage within the next few weeks, and I'll be starting to use more complex visuals in the game. It's a 2d platformer and the engine is compatible with virtually any image format.

My engine is currently based off of the smallest tiles being 16x16 and the average tiles/character sprite being 64x64, but of course, other sprites in the game environment can be much larger. My team is fairly laid back, and you would be given plenty of time to make the sprites. If you are interested, send me a message or email me at claymyers5@gmail.com. We're doing this project out of our love for games and art, so there would be no profit involved.
You would be given concept art to use for the sprites. The character designs are unchangeable, but as the sprite artist, you would have a good amount of control over how the visuals go and I would be open to any artistic ideas you may have.
Any questions can be posted as a reply to this thread and ill do my best to respond quickly.