I've been using SyncToy for as long as it's been available.
Released as one of the .net showcases (IIRC) it basically scans two folders, decides what the latest versions of the files are, and duplicates the two folders with all the latest files intact.

SyncToy Download

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I use this app for all my Backups.
An initial sync/restore can take a ludicrous amount of time, as it scans and checks the hundreds and thousands of files within a subdirectory, along with the similar files on the secondary folder (usually on my NAS drive)

But once it's managed to copy everything across, a daily sync isn't a lengthy issue at all.
It scans fairly quickly, and copies only the changed files.

Many people have suggested I do a "Proper" backup. One of those which leave behind hundreds of weekly Multi-Gig archived files, all over your NAS drive.
I find those to be entirely useless to me.

For starters, "Version Control" is meaningless to me, when entire games get created within the space of a week!
Restoring a "Version Control" file from two days ago would result in me not having anything left, as I'd only just started the project!

Since I hop from PC to Mac, and over to iOS as well, it's also good to have actual access to the actual files.
For example, I might want to change an background image in a game. I can easily load the image up using FileExplorer on my iPad, save it to it's Photos, load it into SpriteSomething, edit is, save it back to Photos, then save it back to the backup with FileExplorer.
I do this type of thing fairly regularly, without having to grab the laptop and fiddle about with emails or, god-forbid, having to use iTunes on Windows.. Arrrgh!!

No, it's all right there on my NAS, and as long as I run SyncToy every day or so, the list of files remain functional and accessible at all times.

But I'm wondering what else is out there, that I might've missed.
Do you have a favourite sync/backup tool?
What else is available for me to try out?!

Let me know in comments, or via email or Twitter.

SyncToy Download