1. A simulation environment comprising: a plurality of debugger clients; and a virtual machine simulator, executing a simulation on a physical computing device, including; a debugger server to control the run mode of the simulation before any debugger clients are coupled to the simulation, to enable coupling and un-coupling of debugger clients to the simulation, and to coordinate run modes of the plurality of debugger clients and to control the run mode of the simulation after the debugger clients are un-coupled to the simulation when one or more debugger clients are coupled to the simulation in response to requests from one or more debugger adapters to the debugger server on behalf of corresponding debugger clients; and one or more debugger adapters, wherein each debugger adapter is coupled between the debugger server and one or more corresponding debugger clients of the plurality of debugger clients, to control run modes of the plurality of debugger clients by each debugger adapter making requests on behalf of its corresponding debugger clients to other debugger adapters through the debugger server to change the run mode of debugger clients coupled to the other debugger adapters to a given state, and to accept or reject requests to change the run mode of its corresponding debugger clients to a given state.