In the last years the appeal for using methane as green fuel for rocket engines has been on an in-creasing trend due to the more facile storage capability, reduced handling complexity and cost-effectiveness when compared to hydrogen. The present paper presents an attempt to simulate the ignition and propagation of the flame for a 1 kN gaseous methane-oxygen rocket engine using a pintle-type injector. By using advanced numerical simulations, the Eddy Dissipation Concept (EDC) combined with the Partially Stirred Reactor (PaSR) model and the Shielded Detached Eddy Simulation (SDES) were utilized in the complex transient ignition process. The results provide important information regarding the flame propagation and stability, pollutants formation and temperature distribution during the engine start-up, highlighting the uneven mixing regions and thermal load on the injector. This information could further be used for the pintle injector’s geometry optimization by addressing critical design challenges, without employing the need for iterative prototyping during early stages of development.