Rogue Gun was a side-scrolling tactical sci-fi shooter I was making in 2008. It was very Halo-esque with toggle-able weapons, regenerating shields, and deployable equipment. It's not my absolute favorite of the 2D shooters I was making at the time, but it is reperesentative of them.
This demo was posted to the Game Maker Sandbox back in the day. I had added some additional enemies and weapons since then, but this is otherwise the state of the game when I abandoned it. I had the emotional/cognitive intelligence of a 15 year old when I made this, so ignore the introductory cutscene. You can hit the spacebar to skip it. I failed to do much narrative implementation after that bit, so don't worry too much about the story.