We (2 friends of mine and myself) recently made a large neo-retro pixel-based video game akin to galaga, robotron, etc. It took us about 8 months. It's got lots of weapons, characters, bosses, etc, and a full 8-bit soundtrack as well. We are giving it all away for free.
You can get some screenshots and download the thing at that address.
Please check it out and let us know what you think!