ultimatum, a 2 player game

there is a pot of money (100 coins)

player #1 can decide how to split up the money
player #2 can accept or decline
If accepted, both players keep their split; if declined, both get nothing

player #1 should choose a 99/1 split
player #2 should accept it

the problem with game theory is that it assumes rational agents

working on meta.matcha.xyz, yc alum, @orangedao

I don't think game theory assumes anything. In my mind GT is more about the possible alternative universes that may unfold given a certain choice. 

My question for your game idea above would be why anyone would want to play that game in the first place. What is the upside?