Delete/reset specific achievements?

[JohnAlekseyev]

Hey there, I am aware it is possible to reset/delete all achievements via the "Settings" -> "Other" -> "Delete Achievements" option. However, I have the following situation:

I am playing with a friend, and we have our achievements progress at the same time due to that. But I did some experimenting in SP and got ahead in some achievements, so I would like to delete these specific ones to get back to the previous state. So I would like to reset several "milestone" ones, such as triggering a stomper attack or landing on planet X, but don't want to delete some challenge achievements that have been completed, like the no-solar and no-laser ones. And there are some that can't even be re-achieved when loading a save, like researching oil processing, since it has already been researched.

I have seen documentation on the achievements.dat file, but haven't seen an editor for it.

[IsaacOscar]

I had a problem where I loaded someone else save and instantly got a bunch of achievements...

I tried to make an editor for that achievements.dat, unfortunately the documentation is way out of date due to all the new space age achievements and I gave up reverse engineering the new one.
I ended up just deleting all my achievements, and cheating to get some of them back.

[JohnAlekseyev]

I guess that will be the way :/