Realistic space warfare, which means using only weapons systems that could be feasible to build today (conventional guns, railguns, coilguns, lasers, particle guns, conventional fragmentation explosives, nukes, etc.) and the same for propulsion systems (Chemical rockets, nuclear thermal/salt water rockets, nuclear pulse propulsion, MPDs, ion engines, laser thermal, etc.). It's almost impossible to find anything on this, I'm lucky to have one simulator called Children of a Dead Earth (Which got me into this) and the website Atomic Rockets.