Create an interactive game

web apps to create games

MonoGame, a free OpenGL implementation of the XNA Framework for MonoTouch, MonoDroid, Mac OS X & Windows

Assets game content

The Reiners Tileset propose a huge collection of animated Sprites with positions in the e-ne-n-nw-w-sw-s-se orientations. All released as freeware. As stated on the readme page freeware "All the graphics, textures and meshes are freeware. Even for commercial Games. I just want my name in the Credits in the commercial case"

A sprite lib under a GPL license

Very nice textures and tilesets shared by Lost Garden: Handrawn textures, 8-bit Sinistar clone graphics, some great sets of game tiles and game graphics for small worlds. They are all released under a very loose license: "As always, these tiles are free to be used in whatever projects you desire. (I need to get a copyleft license available at some point.) If you do use the graphics, drop me a note."

Using google, it is not difficult to find other resources, like this huge collection of resources Charas Project. But I wouldn't recommend to use these for anything other than inspiration.

Open Game Art which presents itself as a "community that brings like-minded coders and artists together for the purpose of creating Open Source video games, by providing a human-edited, searchable database of freely-licensed art resources."

User contributed Game Art Pack in the Dundjinni community (they can easily be reused in other contexts)