Really glad someone brought up F-Zero, my personal favorite racers where [url=http://fzero.wikia.com/wiki/James_McCloud]these[/url] [url=http://fzero.wikia.com/wiki/Mighty_Gazelle]two.[/url].

I was also a huge fan of Custom Robo and would be interested in seeing the series expand to the newer systems.

The ultimate underrated game for me is Metroid Prime, easily my favorite video game of all time. But it doesn't necessarily fit because it has quite the cult following. Still, it is not usually recognized as the true piece of art that it is.

So my two additions would be Metal Arms and Colony Wars.

Metal Arms: Glitch in the System, was the PS2's first reaction to Halo, which explains its failure. The game has a cool setting, interesting combat possibilities, and some really off-the-wall humor.

Colony Wars was a Space Fighter trilogy for the first Play Station. The games were unique in that a failed mission would never lead to a "game over", instead, the plot would take different routes depending on the success of the player, leading to 5 different endings.