and then there’s Fallout 3 & NV, where low skill points in Small Guns makes bullets bend away from the crosshair

Kerbal Space Program / Factorio / Stellaris crossover

Key elements would include:
-design a factory/macro-economy to produce aerospace components & weapons similar to Factorio
-using those components, design vehicles that obey real-ish physical laws similar to KSP
-arm those vehicles and use them as units in Real Time Strategy with the option to take First Person control of individual units