Aha, a verb that doesn't end with -r in the present tense - vet! So it's not a 100% guarantee :p
The complexity arises from the fact that you have three versions in English none, any, and some, that map over to just two in Swedish, ingen or någon. The Swedish system isn't complex in itself, but in order to translate you have to match the two systems correctly.
I think my second comment on this page may be helpful: https://www.duolingo.com/comment/5562715
I think I understand, I just want to clarify a few things. Please tell me if the following is correct:
Någon is an adjective meaning "any" or "some." It's singular en, singular ett, and plural forms are någon, något and några, respectively. Since words like person and människa are en-words and the word ting is an ett-word, one can use någon to mean "anybody" or "somebody" and något to mean "anything" or "something" in the same way that English speakers sometimes use "any" or "some" as a pronoun. Ingen, as we know from the "Questions" unit, is an adjective meaning "no." It's singular en, singular ett, and plural forms are ingen, inget, and inga, respectively. In the same way that någon can mean "anybody" or "somebody" and något can mean "anything" or "something," ingen can mean "no one" and inget can mean "nothing." And in the same way that the English question "Is there nothing you want?" means the same thing as "Do you want anything?" and "Don't you want anything?", the Swedish word for "nothing" can be used to mean "anything" and "not anything."