How do I get a patronymic on the generated Viking name?
Turn on the "showPatronymic" option, or pick the "full" theme, which always includes it. The patronymic draws from 39 father names and applies the real Old Norse genitive rule (the "-i" to "-a-" shift, the no-double-"-s" rule, and the default linking "-s-"), then appends "-son" or "-dóttir" depending on the rolled gender.
What is the difference between the "both" theme and the "full" theme for a campaign name?
Both roll gender 50/50 and can attach a byname by default, but "full" additionally forces the patronymic on, so a "both" result might be just "Sif" while a "full" result is always three parts: given name, patronymic, and byname.
Do the generated Viking names sound like the ones in Skyrim or God of War?
The building blocks are the same real Old Norse elements those settings draw on (Eirik, Ragnar, Bjorn), because the generator uses 48 attested first-elements and 24/18 gendered second-elements from actual saga and Landnámabók sources, not invented syllables, so overlap with any specific fictional universe is expected rather than coincidental.
Can I generate a simple name for a minor NPC, without runic spelling?
Yes: turn off both "showPatronymic" and "showByname" and pick the "masculine" or "feminine" theme instead of "full". The result is a single given name, either one of 56 attested historical names per gender or a freshly composed one, with no byname or patronymic attached.