Atsushi Inaba and company had to have realized how commercially infeasible such a Hard Core Real Robot simulator would be, requiring a US$200 controller bundle and an original Xbox if you didn't have one already, and the Roguelike approach to saving and death and no pause feature.
They are considered two of the very best games on the PS2 and any conversation about "games as art" will inevitably include a discussion of these particular examples. Neither ICO nor Shadow of the Colossus sold very well, but Sony continues to fund and support Team ICO because ICO and SOTC were met with universal acclaim from the press and gamers alike. The best words to describe it: "A labor of love by fans of Half-Life."
All the effort of an officially licensed game, but entirely free to the community.