Pressure Cooker
A term to describe a certain play style (either intended/designed for or happening organically) where "public" outbursts of drama are rare, taboo or even forbidden, and the visible drama is kept "out of public view", or kept entirely inside. In "pressure cooker" larp participants are encouraged to let conflicts and emotions simnmer beneath the surface, letting tensions build, and avoiding big public "reveals" or fights, sometimes with the designed intent to let it all explode in the last act and sometimes to just keep on simmering.
This play style creates a sense of pressure building up inside (like in a pressure cooker) because what the character is feeling or experiencing cannot be expressed outwardly and has to be contained or controlled. In designs where players are encouraged to "let the pressure out" in the final act of the larp, it can sometimes lead to plot reveal fatigue.
Origins
One of the first larps to use the term was Brudpris, in which the fictive society was strictly regulated and any emotional outburst was seen as taboo and dangerous.