Excited electronic states of small molecules can be efficiently calculated with conventional quantum-chemistry methods like CIS/TD-DFT, MPn/ADC(n), EOM-CC, and CASSCF/CASTP2. However, these methods scale unfavorably with system size, making the calculations unfeasible for large multichromophoric systems. This limitation can be overcome by using an exciton model, where the states of individual chromophores (site states) are computed conventionally, and then used to construct a simple exciton Hamiltonian of the full system.The ECI2GAME project aims to develop a general and efficient electronic-structure method for multichromophoric systems based on the recently introduced Excitonic Configuration Interaction (ECI) concept. The resulting ECI method will (i) have near-linear scaling with the number of chromophores, with minimal error compared to conventional methods; (ii) handle states of arbitrary multichromophoric character, such as (multi)local excitations, (multi-)charge-transfer states, their combinations, etc.; (iii) be independent of the conventional method used in site-state calculations, allowing usage of diverse types of the site states; and (iv) be able to treat the systems with moderately strongly interacting chromophores.The methodology will be implemented in the SHARC package, which focuses on surface-hopping simulations of molecular nonadiabatic dynamics. Hence, once developed, the ECI method will also enable real-time simulations of photoinduced processes in multichromophoric systems, such as Förster/Dexter energy transfer, singlet fission, charge transfer, etc.The approach will be applied to study the photochemistry of human DNA segments most prone to UV-induced damage. This will elucidate the processes happening in the first few picoseconds after the UV absorption that influence the fate of the DNA on the long timescales. Additional photochemical studies on other relevant multichromophoric systems are also planned.