Halo: Out With a Whimper

Halo: Out With a Whimper was a side-scrolling shooter take on Halo's Firefight PvE mode and served as a gameplay demo of sorts for their previously upcoming game Halo: Olympus, cancelled as of 2013.

The game is set around the events of Halo 2 and Halo 3 on the human mining colony Atlas as it comes under siege by the Covenant, who are looking for something hidden beneath the planet's surface.