As the name suggests, daily missions are randomly generated missions that you can complete only once a day. Once the mission is complete, you must wait until the next daily reset (12 UTC) to play it again.
How do I play Daily missions?
Daily missions are available to all players after completing the first 8 Primary Missions in Tonka Bay. You can access the Daily Missions from any city by clicking on the "Daily Mission" pin.
How does it work?
Daily missions work a bit differently from regular missions, as you do not use your own weapons. Instead, you get temporarily lent a weapon by Boss (the protagonist who assigns you the missions). This can be a great way to try out weapons you'll have possibly overlooked otherwise.
Completing a Daily mission will reward you with some gold coins, which you can use to buy and upgrade weapons. You will also receive bonus coins for each headshot!