Pixel Vision 8 was designed specifically for game jams. Not only can you customize the look and feel of your game with the Chip Editor but you can also use Lua to prototype ideas in a short amount of time. Think of Pixel Vision 8's Game Creator as a sketch pad for making 8-bit games.
There are two versions of the Game Creator to chose: free and pro. The free version contains everything you need to create an authentic looking 8-bit game.
The Pro version has extra tools that allow you to preview and edit system colors, sprites, tilemaps, sounds and music.
While you can modify all of these files with external editors in the free version, the Pro tools are incredibly helpful for debugging and speeding up your development time.