Mixed Reality (MR) Games integrate digital elements with real world places. In doing so they change those places, with important ethical implications. We present a synthesis of 8 existing frameworks on MR Ethics to establish a set of ethical issues for MR Games, and a qualitative analysis of interviews with 17 MR Game Designers to define the strategic approaches they use to address them. We identify 26 ethical issues over 5 dimensions: Claim Rights, Duty of Care, Social Justice, Privacy, and Control; and 59 separate tactics forming 13 strategic approaches over three areas: Design, Participant Management, and Logistics. Mapping these to codes of ethics from the ACM and IEEE we show that the strategies can be seen as methods for behaving ethically within the context of MR Game development, although many strategies rest on the virtues of individual designers and their critical engagement with an ongoing ethical process.