sorry for the late reply.
Its a matter of content not "interactivity", the critic has to see majority of the content before he gives a review. It is the same thing with a movie or books, for example there are "choose your own adventure" books should critic take only one of dozen paths in story and then give a review.
it is indeed a matter of content. can you play a game, see less than 100% of its' content and still be able to make a decent review?
yes.
can you do the same with books or movies?
no.
or are you implying that any and every review out there is based on 100% play-throughs? that the reviewers of fallout 1 and 2 played every little side quest and explored 100% of the game world? that that the reviewers of crysis killed every enemy and explored every square cm of the map? that in a sports game review, the reviewer player every mode of the game, with every team against every other team in any possible combination and permutation?
the thing is that with games you can definitely base a review on your experience, even if it does not equal 100% of the content. especially if you are playing with a review in mind. you play, focus on the core aspects, like story, rpg elements, interface, etc., finish, make the review.
example: i've been playing Clear Sky for roughly 20 hours now. and i already know that
-it's buggy as hell
-it's hard as hell
-the AI is unbalanced as hell
-the story is decently made but usually revolves around tasks of the "i-can-help-you-but-like-to-send-you-on-suicide-mission-first"-kind.
-it looks great and has great atmosphere
-it good fun.
i could write a review now, without having finished it.
in short: reviewing games != reviewing books/movies
(i omitted the "choose your own" kind of books, since they are a niche and i can count on one hand how many i've seen of those, let alone read)
The job of a critic is to explore the game and make a score of what he saw, not to finish the game as fast as he can and i dont know of anyone who finished Fallout 1 in less than 20 min. Like watching an a action movie but fast forwarding to action scenes ignoring the rest of a movie, yeah the action scenes are great but what you didnt see is that the story sucks.
as i said, you can finish a game reasonably fast but STILL be able to witness and document the defining factors.
as for fallout in 20 minutes: youtube is your friend.