Defining “Player Solipsism”

My friend Inumo reached out last week about a topic we had discussed a number of times before, that I haven't really seen discussed in broader roleplaying game discussion. A while ago I coined the term "player solipsism" to refer to a school of RPG design that is based around a fundamentally different set of principles from simulationism. A while ago Inumo wrote a sketch getting into these ideas,…