The technique has improved since then, the methods to crack it but also turn. The eternal cat and mouse game between team blue and team red.
So, apparently the first sentence means that the technique has improved since then, but so have the methods trying to crack it.
Though, to be fair, I have no clue what rumgeilt means and that was apparently just not translated at all.
Is what it was trying to translate, not sure where you/it got 'rumgeilt' from.
A more natural sounding translation would be:
The technology has improved since then, but, on the other hand, so have the methods to crack it
You could also translate 'wiederum' as 'in turn' which might exlain the 'turn' in Google's translation.
I know a little German, a little French and took Classical Greek in college, as well as Intro to Linguistics (where, iirc, we covered a bit of Swahili grammar for some damn reason). I am pretty comfortable with both weird idioms not translating directly and with finding close, if uncommon, matches between some other language and words or phrases in English. So, the "in turn" part doesn't disturb me. I mean, you could translate it as something like "They are taking it in turns" or "but the methods to crack it also got their turn to improve."