This is as short little ROM demonstrating animated backgrounds on the NES using the MMC1 mapper with CHR RAM. The animated image is 8x8 tiles (64x64 pixels) with three colors that tiles seamlessly across the screen. A "snake" is present to demonstrate the redrawing of the correct animation tiles onto the background.

You'll need the following pieces of software installed to build:

• Git
• Make
• Go (for go-nes dependency)
• cc65
• Aseprite (optional)

Then it's just three commands:

$ git clone --recurse-submodules https://github.com/zorchenhimer/nes-animated-background
$ cd nes-animated-background/
$ make

The background animation was made using Aseprite which a paid program. The exported bitmaps have been included in this repository to avoid requiring this program to build the ROM. Note that the make cleanall command will delete the bitmaps in the images/ directory to trigger re-exporting them using Aseprite. If this is done in error, simply use git to restore the images: git checkout -- images/*.bmp.