You cannot simply click "Download" and play.
While "nsp" files are often associated with unofficial distributions, you can legally download the game through these official channels: Bulletstorm: Duke of Switch (Switch) Review bulletstorm duke of switch edition nsp free hot do
The Duke of Switch Edition is a decent portable version of a fun but flawed shooter. It’s a must-own, but it’s entertaining if you like crude action and don’t mind technical hiccups. For “lifestyle,” it’s a game you pick up for a weekend, not a long-term commitment. You cannot simply click "Download" and play
Since your search included "lifestyle and entertainment," here is how Bulletstorm actually fits into a gamer's lifestyle safely: bulletstorm duke of switch edition nsp free hot do