Valheim: How the heck has more 'indie shovelware with PS2 graphics' sold 4 million copies in a matter of weeks?

Now, this might shock you, but it's something we like to call 'fun' (if you have friends)
The RPG Greetings, traveller, and welcome back to The Register Plays Games, our monthly gaming column. Loath as I am to feature another early access survival-exploration-crafting adventure for the second month in a row, February's sleeper smash-hit, Valheim, has forced my hand. So onwards, now, to the 10th realm of Norse mythology. Yeah, there was an extra one, didn't you hear?…