I think dayZ coul use player triggered events linked to mini-bosses: killing the rare crazy doctor at hospital could trigger medical supply drop, killing butcher at supermarket could cause mass zombie spawn, killing general at base could trigger helicopter crash (to be fixed), killing lumberjack in woods provides survival kit, killing zombie engineer in power plat causes gas leak & explosions. Killing the zombie poliece in towns increases zombie spawns. Killing enough poliece causes a zombie poliece chief spawn. Killing zombie chief reduces zombie spawn for 6hrs. I would make these bosses obscenly tough.