I'm a solo programmer which needs a pixel artist for my game Switch-It. Past experience has shown me that new graphics can enable a game to grow immensely. My game Battle Arena is a great example. Thanks to new graphics it has recently reached 500,000 installs!
I would new sprites. A character walking then running then cycling as the game speeds up. Instead of the cube switching colour the character will change outfit to match the season. So the character will switch from an umbrella and a rain coat to some summer clothes with a click.
The objective is to always have the proper outfit for the season. A rain environment will have to be created, drops falling on the umbrealla... And of course a summer environment will have to be created.
I don't have big budget (100$ negotiable) but I think the game has a huge potential. If you want to be part of the project, and help Switch-It be the next popular game; reply to this post or email me at diogovaldivieso@gmail.com.

Switch-It: (https://play.google.com/store/apps/details?id=com.Company.SwitchIt).
Battle Arena (https://play.google.com/store/apps/details?id=com.BattleArena.com)