Some ideas for sand box type games.
Missions with timed availability.
The idea of this is that missions can have certain times of day that they have to be completed at. You might think that would be annoying but missions are only shown on your map that you could reach in time to start from your present location. So there would be no chance of going to a place and then waiting for the right time of day. The advantage is that the mission can be structured around a certain time of day, ones that give a required level of visibility or cover of night, or just a time at which the location looks really good. Weather conditions could play a part as well. This also allows a changing world say an area has been conquered by an army then the missions in that area change. You've run out of time to do the missions that were previously available, one's that wouldn't make sense in the new status quo. Could add to replay value.
Dynamic mission structure based on angle of entry into mission area.
Sand box games should be about options and the starting place of a mission should be one of those options. Say you've got a mission to assassinate someone on the 13th floor of a building. The building becomes a boundary box that the computer knows where you are entering it from. You can go in from the roof, a window, the front door, back door or some other entrance. Then based on your entry point the enemies are in different positions, on different states of alert.
Missions with timed availability.
The idea of this is that missions can have certain times of day that they have to be completed at. You might think that would be annoying but missions are only shown on your map that you could reach in time to start from your present location. So there would be no chance of going to a place and then waiting for the right time of day. The advantage is that the mission can be structured around a certain time of day, ones that give a required level of visibility or cover of night, or just a time at which the location looks really good. Weather conditions could play a part as well. This also allows a changing world say an area has been conquered by an army then the missions in that area change. You've run out of time to do the missions that were previously available, one's that wouldn't make sense in the new status quo. Could add to replay value.
Dynamic mission structure based on angle of entry into mission area.
Sand box games should be about options and the starting place of a mission should be one of those options. Say you've got a mission to assassinate someone on the 13th floor of a building. The building becomes a boundary box that the computer knows where you are entering it from. You can go in from the roof, a window, the front door, back door or some other entrance. Then based on your entry point the enemies are in different positions, on different states of alert.