I've been watching this game for awhile now and it looks very promising. There's even a demo of the game that can be downloaded. The game is indeed made with game maker and I believe that all the types of metroids are custom sprites (alpha, gamma, zeta, omega, and the queen). Samus is just the zero mission sprite. Anyways I've played the demo and enjoyed it, can't wait for it to come out. I think he said he was hoping for it do be done sometime this year.
Oh and the second link there DH is a different remake, I'm pretty sure it's still in development but no the guy hasn't announced anything since his site was hacked.