The aim of this work is to analyze the behavior of the fuel flexible Ansaldo ARI100 T2 microgas turbine (MGT) combustor operated with mixtures having different H2, CH4, and CO2 concentrations. This combustor is going to be installed on an in-house modified Turbec T100 P MGT, which is originally equipped with a methane fired combustor. In a previous study, the combustor was simulated with a H2 enriched syngas, whose Wobbe index was within the limits imposed by the syngas supply system of an Ansaldo test bench. In this study, this constraint has been removed to gain a deeper understanding on how the fuel mixture properties (composition, heating value, and laminar flame speed) affect combustor performance. To this end, a series of Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) simulations have been carried out on the full-scale 3D geometry of the combustion chamber, at full and partial load (50%), evaluating for each case combustion efficiency as well as NOx and CO emissions.