Making checkpoints and make them WORK

[Tanshaydar]

Then you should activate the checkpoint before picking up the key, with a script area or else; and remove all "Remove Callback after interaction"-like checkboxes for the key interaction callbacks.

I might be able to help if you pm me, but know that I'm still a noob to all these things.

[Pandemoneus]

AutoSave just creates a savegame, but you can't load it automatically.
The devs made a few scripts that trigger when you die, so other things happen and so on. You will have to implement something like that aswell or take a look at the original script files.

[Tanshaydar]

I'm searching game's hps files, but I couldn't find a proper script to do what is needed: making the key untouched after touching and dying.

[Beatlebattle]

I'm not familiar with those scripts either. By the way Lev4.hps has 2 times

void OnStart()

You might wanna change that in yours too since the map isnt loading

[Tanshaydar]

Well, that's no problem, but for the problem here only thing I can think of is to load manually a save.

There is one more solution, but it's really dumb and hard. And for each death, must be implemented, so it's not really a solution.

Main game itself has this issue too, once you die, monsters disappear...