The only game that I know of that tackles war as a psychological thing is Spec Ops the Line which is a brilliant game that is now delisted on steam for reasons. Regardless I do think the reason war is rarely shown in such a way is that the artistry (for lack of a better term) is relatively hard to balance between story and gameplay. Not even getting into how hard it is to tell such a story, making True Grit 1969 is a lot easier than making True Grit 2010.