The development of quantum simulation lacks compact on-chip scalable platforms. The recent demonstrations of polariton lattices in semiconductor microcavities, in combination with their extraordinary nonlinearities, place polaritons as one of the most promising candidates to achieve this goal. The aim of this proposal is to implement polariton lattices in semiconductor microcavities as a photonic-based solid-state platform for quantum simulation. The polariton platform will allow for the engineering of the lattice geometry and site-to-site hoping, injection and detection in individual sites, sensitivity to magnetic fields, and scalability due to the low value of disorder. The driven-dissipative nature of the system opens the exciting possibility of studying out-of-equilibrium strongly correlated phases, but it also calls for new theoretical methods. We will join the expertise in semiconductor technology of four experimental groups and the input of two theoretical groups to push polariton nonlinearities into the strongly interacting regime. We plan on implementing the first polariton simulators by studying quantum correlations in few coupled resonators, and the topological properties of 1D and 2D dissipative lattices, both experimentally and theoretically. This project will provide the first quantum simulation platform using scalable lattices at optical wavelengths. This project aims at the development of the world-first polariton quantum simulator, an entirely new platform for Quantum Simulation. Therefore, it is directly relevant to the second Targeted Outcome of the call. The new platform will enter the strongly correlated regime, thus enabling simulations of some of the most fundamental strongly interacting quantum models. In contrast to other platforms, it will operate on-chip and at optical wavelengths, which will make it also applicable for Quantum Communication technologies (the first Targeted Outcome of the call). The proposed research also incorporates the development of new strategies for the verification of quantum simulations (the second Targeted Outcome). In parallel to experiment we will research theoretical methods for dissipative strongly interacting systems. This will lead to the development of new techniques applicable to non-equilibrium strongly correlated systems, which are still very limited. Our methods will be verified by comparing them directly with the experimental data.