I was thinking about a horde mode for destiny, enemies running out like at The Dark Below when you've woken the hive. 3 player against VS Environment Chest respawning at different areas in the map (like zombies on CoD) and the chest is extremely random because this mode is more about staying alive longer than your online friends, rather than using it for loot. And then there can be a Hard Mode too, where you only can gain ammo from dead enemies and maybe an extra Major enemy or whatever. Add some ideas if you're interested.