Play it if: you've got a few minutes to kill and a few brain cells to waste.
Don't play it if: you want a bit more ambition in your IF than - well, almost nothing - and if you are easily enraged by the dumbing-down of the character of Conan as portrayed in external works.
A seemingly one-note joke of a game that actually does have a few puzzles, I'm not sure whether to praise Conan Kill Everything for keeping its admittedly simple premise brief, or wonder if a longer pastiche of the (now ubiquitous) dim-witted caricature of the character is in order.
But I won't be too picky. This is a fairly funny game, and the point of the joke is made. There are even some minor puzzles and a number of nice touches like Conan's reactions to kissing or cutting things. In sum, it's an OK time-waster.