It's not much, but it's probably the first game that I've actually sat through with until 'completion' - Jball (a Jezzball Clone)

If you remember the Windows "productivity" pack for Windows 3.0 and Window 95 then you probably remember jezzball. It's a pretty simple game -- a few balls are bouncing about the screen and you try to capture them in small areas by placing expanding rays on the screen. The level is over once the balls have been captured in an area equal to 25% of the screen space.

Screenshot

Video of the original Jezzball

Source and executable instructions here

It's not super polished, but it has all of the basic elements of a video game :)

If anyone wants to take a peek at the source and make some comments about my programming I'd really appreciate it.