This..."Cave Story". I've heard of it in various places as being quite good, but, like, what is it? All I know is that it's some sort of Castlevania-y thing.
You don't know what you're missing. It's a freeware, cross-platform, full-lenght 2D RPG/Action game developed entirely by one man. Within 5 years of free time, he independently made the music, the graphics, the characters, the plot and the coding. All by himself.
It's an interesting and a good game really. It can be compared to most 2D games made nowadays. It's really good. Get it noooowwww