In April 2023, a year after its adoption, the Liechtenstein Institute on Self-Determination held the first-ever simulation of the United Nations (UN) veto initiative (UNGA RES/76/262). A subsequent simulation took place in March 2024. Passed amid criticism of UN Security Council inaction in response to the war in Ukraine, the veto initiative resolution aims to enhance the effectiveness, accountability, and transparency of the UN when it comes to matters of international peace and security. In the simulations, we tested scenarios for the implications of the veto initiative for the relationship between the UN Security Council and the UN General Assembly, and for the legitimacy of the UN as a whole.