MilSim (Military Simulation)
generally combines airsoft play with some military live action role-playing elements. Several goals or missions are assigned to each team, along with a basic loadout of ammunition (6 millimeter pellets), rations, batteries, and other suitable equipment.
The teams will remain in the field for the duration of play, only returning to a staging area or "safe zone" for medical emergencies, or other such circumstances.
MILSIM-games often last several days, for example the large BERGET-event in Sweden lasts 6 days in a row, with no breaks. In larger scale MilSims vehicles as simple as painted vans and trucks will be used. But in some cases, such as Operation Irene, real APCs and tanks will be used.