More similar to 010editor. But free, open-source and with a quite nice workflow. The expression language and the back references are a bit hacky though. Maybe a complete separation between the declarative data layout and parsing instructions would have been a better fit.
You learn by doing. Simple as that. Pick a game you really like and try to crack its save system. Use a hex editor to look at the inner workings (I recommend 010 Editor) and try to either modify or break the game state.
Try to find "clues" in the hex output:
If the game is very popular, open source tools are probably already available. A good learning exercise could be to port an existing tool written in C to Python, for example.
Added - Notepad++ may fail at 2GB. Here are a couple of other possible editors from this thread: https://stackoverflow.com/questions/18208524/how-do-i-read-a-text-file-of-about-2-gb
Glogg http://glogg.bonnefon.org/
010 Editor http://www.sweetscape.com/010editor/
I'm not sure you need one - I don't know what you want to do. You seemed interested in knowing how to access something in terms of 1s and 0s.
Hex editors are just computer programs. They're like text editors but they work on binary files. I've used the trial version for 010 editor whenever I've had need for one, which was namely whenever I was trying to reverse engineer the structure of some binary file format.
[](/b32 "It's beautiful. It hangs firefox on every new reddit tab for a few seconds every time.") [](/rb32 "And if you ever need a text editor to handle huge files, http://www.sweetscape.com/010editor/ 010editor did a fantastic job.")
They call it a template. I don't know if it's unique to 010 or what, but it's neat.
http://www.sweetscape.com/010editor/templates.html
They also have a similar function called a script, not sure what the different purpose is for it. If you download the demo they have some sample scripts and templates included, like a PE template so you can change things without necessarily screwing up the binary. I've been using it to try to reconstruct the format of a binary file for a PCB editor which is kicking my rear end. My biggest complaint is that there aren't enough how-to-style examples for people getting started - there's a quick getting started guide and then a bunch of complicated examples. The FAQ helps though.
One neat application is that you can write a template that lets you click on the hex dump and the template will "execute" from there. In my data file they use a lot of length-prefaced strings and apparently-poorly defined segments which this feature helps me recognize - just click and see if it's right or wrong, then recode the template to include them more permanently.