How do you store high scores, game states, or anything you want to keep safe for an arbitrary amount of time. EXPORTed variable are not reliable for this use, and I can't find a way to create an actual User Variable programmatically. Pre-defined vars are the way ? Sounds odd to me...
Thank you for any advice !

Yup, removing EXPORT before variables makes the variable "super global". I don't know how to say it, but there are three types of variables on the HP Prime:

-Local: Declared at the start of a function, only useable in that function and cleared from memory once returning from the function
-Global: Declared with EXPORT at the start of the program, useable through the entire program. The variable is deleted once quitting the program.
-External: Declared without the EXPORT command, still at the start of the program. This type remains intact once exiting the program and can be used anywhere.

In TI and Casio BASIC, however, we can edit variables as we wish, so people can fake highscores and cheat in long RPGs. Even if only the source HP PPL program has access to a declared variable, can that variable still be edited with an on-calc editor or something? Also another question: When using ON+SYMB or pressing the RESET button, are variables cleared? If so, then is there a way to ensure that variables are reset-proof? Else, this might be a problem for role-playing/adventure games like Legend of Zelda or Final Fantasy. Since the HP Prime isn't that stable, we sometimes have to reset it to bring back normal behavior, and it would suck to have to backup our progress on a computer every two hour or so...

Yup, removing EXPORT before variables makes the variable "super global". I don't know how to say it, but there are three types of variables on the HP Prime:

-Local: Declared at the start of a function, only useable in that function and cleared from memory once returning from the function
-Global: Declared with EXPORT at the start of the program, useable through the entire program. The variable is deleted once quitting the program.
-External: Declared without the EXPORT command, still at the start of the program. This type remains intact once exiting the program and can be used anywhere.

In TI and Casio BASIC, however, we can edit variables as we wish, so people can fake highscores and cheat in long RPGs. Even if only the source HP PPL program has access to a declared variable, can that variable still be edited with an on-calc editor or something? Also another question: When using ON+SYMB or pressing the RESET button, are variables cleared? If so, then is there a way to ensure that variables are reset-proof? Else, this might be a problem for role-playing/adventure games like Legend of Zelda or Final Fantasy. Since the HP Prime isn't that stable, we sometimes have to reset it to bring back normal behavior, and it would suck to have to backup our progress on a computer every two hour or so...

This is incorrect. LOCAL is restricted to inside a BEGIN END; pair. EXPORT makes global variables accessible system-wide. Removing EXPORT creates a variable "global" only to the source file. Programs from a different source file cannot see/use these variables, nor can the user. Whether EXPORT'ed or not, both global types remain and retain their values after programs complete their execution until next compile-by-exiting-the-editor event. An ON-SYMB does not clear global variables (not their existence nor their contents).

http://www.hpmuseum.org/forum/thread-215.html

While a non-EXPORT'ed global variable cannot be directly edited by the user from the command line, there is nothing to prevent the user from manually editing the source to "cheat" in games provided they know how to make the modification.

Looks like non-exported globals works like exported ones. It stores values for some time but just entering and exiting program code reset them. That's not a very reliable way to store things.

EDIT : in fact you can read an modify a user var in a program, but not create one, or I didn't find how at least...

It should be possible by making an App maybe, as apps have their own variable name space and settings for each app can be stored (according to inline help).

I don't know, didn't test it yet. I first thought that any program could be turned into an app but it looks a bit more complicated than that.

For me the best solution would be to allow User vars creation programmatically.

In my very humble opinion, trying to prevent people to look at programs code they installed on their calc only for this reason seems a bit disproportionate. I think the way the OS works is broken at the moment, and finding workarounds now is just like putting bandages on a wooden peg (if that makes any sense in english ^^ ).

Reading other's code (and tweak it) is the best way to learn. People will want to read the code, and putting a sword of Damocles saying "Don't open or you'll loose your score/progression/precious data" is not the way I want to make programs.

Prime is young enough and HP people is still working on it, let's report and claim, I'm sure a solution will be found (I'll stick with Users vars, until something better is suggested :p ).

For my part I'll use a Home List for now, with a warning at first launch. I know it's not ideal at all, but at least user can save their list in a user variable and restore it at will. Best compromise I found.

Yeah I don't like the idea of closed-source myself since it prevents people from learning as much. Such password protection would only be a las resort solution to the accidental openings of source. I prefer that HP just fixes super global vars so they remain intact until reformatting the calc.

Right now, a Zelda game for the Prime is impossible without weird workarounds