Downfall was inspired by Spike Goes Down for Vectrex and Man Goes Down on VCS, both by Alex Herbert. It is not intended to be a port or recreation, just the teams imagining of a falling/gravity game idea.

The object of Downfall is to guide your character through a never-ending chasm on a series of platforms, carefully avoiding rising above or dropping below the viewable area of the screen. Reboot have released the game free for download in ROM, BJL, and CDI format. The source code to the game is also freely available to download from the Downfall website.

http://dbug.kicks-ass.net/reboot/web/downfall/about.html