Can you give some restrictions so it is easier ? On what platform do you want to dev ? 2D or 3D?
What genre of game?
Sorry! I missed that its limited on 2D
the platform can be varying, i always loves to find ways for different platforms, or different control ideas so I don't want to bother you with these type of restrictions
i want you to go on, let it out whats in your mind, what could be sort of interesting as a game, be truly free and open minded ^^
this means i dont want any specify any genre (but i guess everyone had enough from simple "platformer adventure" games)