How to handle user save games?

Question

I started on my first game; and now im confused how to handle the player SaveGames. I use google-play-services to persist the user's save games across devices, and I am keeping a local save too.

So the problem is how do I manage conflicts (server vs local). I have attached Save DateTime on he file and there is general data included.

So this is what im doing right now :

• I check the number of coins and gems, the level the player has and if all those are greater than or equal to the other save, i take the first save;

• In all other cases i ask the player what copy to keep; displaying the infos in each save file;

I would like to minimize asking the player which file to keep; (These problem arises only if the player uses multiple devices; Or sometimes he plays locally for a while; and signs in to his acc which already has a save file)

I think you get the idea. I would like to automate everything and dont want the user to go sad just because he misclicked on the local-copy when he had awesome stuff in the server-copy.

I need the idea please :)

Answer 1

If you completely trust your client, or don't care if they mess around with the save file, simply keep some sort of incrementing counter in the save file. Then you can easily tell which save file is newer. Datetime seems like the right answer except it may break if your clients clocks are out of sync, if they set their clocks forward etc. Game variables that don't always increment, like gems or levels, is also bad - what if they don't increase, what if they decrease? The counter can be the turn number if your game is turn based, or a "game clock" that is incremented by the game, based on frames.

If you are worried about the client manipulating the save file, remember that the save file time/counter is not the only thing they could manipulate - anything from scores, levels, achievements - so check out this question: How can I protect my save data from casual hacking?

If you go the route of server-only saving, you need to guard against other kinds of cheating. Check out this question: How can I prevent false score reports to global highscore tables?

But keep in mind that, unless there is a multiplayer component like global high scores, or the game is monetised, requiring players have an online connection to save in a single player game is a very anti-player design.