Time in Games

Hi, I've been trying to figure this out for a while and can't find anything on it. I want to know how one makes Time based game objects like in Clash of Clans. Like for example it takes 2 hours to upgrade a certain item. My question is where is the time stored? When the player comes back to the game an Hour later how does the game know an hour went by?

Another example Candy Crush when a timer counts down and like every 15min or so you get a heart. and if you comeback 30min later the player has 2 hearts. Where is the Time Stored?

Thanks.

 

http://answers.unity3d.com/questions/212169/countdown-for-iphone-that-continues-while-the-apps.html

 

Simply put, you schedule it. You say that this is going to be done at 4:30, instead of in three hours, so that it's easier to track using real time.

 

Thanks guys, I thought about the saving of the time and then subtracting the current time, but was not sure. Scheduling the time seems good but what if days go by then I guess i'd have to get the date and subtract or add 24 hours for each day that had gone by..

 

That will allow people to cheat by just changing their system time. The thread carking posted will help you.

 

So? If it's a single player game then whatever. If it's online, then the server should be doing most of the lifting anyway. Hell, it's just as easy this way to incorporate it into an in-game day/night cycle or other time mechanics. The important thing is to be thinking about time differently from the countdown that people normally see. If you start having a lot of things counting down, it's much more efficient to have a sorted list where you only need to check the first entry to see if it's time for it to be ready, then to have to iterate through the list and decrement each timer.

Also, I'm pretty sure what carking posted will have the same issue. All it seems to do is grab system time and convert to UTC.