Massive stars are fundamental drivers of the Universe because of their injection of energy, momentum, and nuclear-processed material in every stage of their life and death. Their feedback depends on their formation, winds and evolution, and these in turn depend on chemical composition. The GTC-OSIRIS combination is an excellent machine for quantitative studies of blue massive stars in Local Group galaxies, where different metallicity environments can be probed. We present our analyses of OSIRIS spectra of blue massive stars in IC 1613, where metallicity ranges from ~0.05 to 0.1 Z_⊙ according to HII regions. GTC-OSIRIS unveils unknown O-type stars in IC 1613, whose quantitative analysis will provide new insight for our models of massive star winds and evolution and will serve as proxy for studies of the early Universe.