Not sure if anyone has heard of this game, but Cave Story is an amazing, FREE, game, which I can honestly say is better than many games I would PAY for! One person made this entire game over the course of 5 years!
From the site:
The gameplay plays like a combination of various NES/Famicom games. Some that come to mind are Metroid, Castlevania, Megaman, Blaster Master and Monster Mash. Pixel’s art style and character design and boss battles are very reminiscent of Treasure games, like Gunstar Heroes, which happens to be one of my personal favorite games of all time. So if you are a fan of any of these titles, then you are in for a real treat. It was a wonderful and addicting experience playing through it and I hope anyone reading this who has not already played this game will give it a shot. You won’t be disappointed. It reminded me of why I enjoy playing videogames.
Try it out at
http://www.miraigamer.net/cavestory/csdeluxe.php