Translation:It was pure fun without compromises.
Unadulterated or pure fun, yes, absolutely. Without compromise sounds odd in English*, though; you can say it, but one wouldn't. The concept makes some sense, but as a rule you don't use compromise that way - if someone learns this sentence from Duolingo and uses it in conversation, he'll get odd looks.
So good English might be going a little too far. I wonder whether Duo would accept any of your other versions? They all feel more natural to me.
*I am a native speaker of American English, I can't confidently assert this for all other dialects. But I've never heard it.
I suggest you make improvements suggestions in general threads such as https://forum.duolingo.com/comment/29608828/Is-the-Italian-tree-too-short. Usually the Duolingo staff does not read the comments in the threads of the exercises such as this one.
"without compromise" (in singular) is the most usual expression in English.