Don't even bother. If a person wants to cheat, let them cheat. They bought the game. Let them play it the way they want.

This is of course assuming we are talking about single player games where cheating doesn't affect anyone else.

Imagine a game like X-Com (which I haven't played, but I know the basics of). Due to the use of random numbers to determine if an alien is hit, or if one of your troops dies, or even the A.I. decisions, replacing a save file can help because next time the random numbers will be different different. So, why not make them the same - load the state of the generator from the save file and continue to use it going forward. So the next time the player loads the game, the same stream of numbers is waiting to be used.

The latest version of X-Com that I've played has a "Save Scumming" setting for whether it saves its random number seeds. I don't know if it's one global seed, per team, per soldier, per action, or something else. Generally, if I reload after some bad dice rolls in a strategy game, I'd just retreat or find cover. I wouldn't try to do the same thing over and over. If I knew I was due a "hard time", I'd make sure I was in good cover and as far away as possible from the enemy, and I'd try to use up my inaccurate shots, so there's still a way to game the situation.

You could use an NTFS alternate data stream. Very few people know about them, and it would take someone with a disk I/O monitor to realize what you're doing.

To make it harder for someone to notice the ADS in a disk monitor, you can put the ADS *on the folder itself* with the same name of a standard, red herring file in the folder.

Example:

Folder:Save1.dat <- this is the ADS

Folder/Save1.dat <- this is the red herring (just write a ton of random bytes to it to make it look encrypted)

The : and / will be hard to spot in the disk monitor and it may appear to the cheater that only one file is being accessed.

Here's the fun part: Copy/pasting something with an ADS attached to it *does not copy the ADS*. This means that if the player makes a backup of their save folder, then restores it later, the original ADS will either be unmodified or completely lost.

The most obvious downside is that people unaware of the ADS will not be able to make any kind of backup of it. If they try to copy the game to a new computer, their game will be lost.

It's not perfect, but it'll probably confuse the hell out of people for a while. Still, it only takes one person leaking the information about how it works for the technique to be ruined.

The way nethack does it is by running the game with the s-bit set (as root). So when the player saves, the data gets written to /var/games/nethack which the user has no write access to. This means on shared systems where the user has no admin access, they effectively cannot interfere with the save file.

So some flaws...

1) Nethack is open source so you can modify the code to remove the requirement.
2) Copy the binary, drop the s-bit and hex edit it to point to your home directory
3) chroot to create a fake root environment where you have control over the save file

I would just like to point out that saving the game remotely adds complexity and further requirements to your project without providing a feasible return in most cases. Intercepting the call for a save game file and injecting your own is a lot simpler, in many circumstances, than performing intense decryption. Many forms of encryption, worth a lot more than any save game editor, have stood the test of time for dozens of years.

Hi
In many games such as xcom or others, there is a big point in the player not being able to go back if something went "bad". Actions should be permanent. The punishment/difficulty for "failing" something ingame can differ, but generally you don't want the player to be able to cheat.

However it seems to be hard to technically prevent save cheating (the user just finds and backups the "savefile" and restores it later). Any good way to actually stop this from being possible? Hide or nest files or something? I mean, if i save progress in the exe instead of in a separate "savefile" the player can just backup the exefile...

I was wondering the same thing but for single player games (will probably never make an mmo/mo etc.).
I guess i/you could implement an automatic autosave without the option for 'no autosave' and when the player opens the game, you can only load your career (like nfsmw).

He's already stated that this is basically what he wants to implement. His question is "how to stop people from cheating?"