The game is Guess the Movie from the Screenshot.
It's very easy, you don't need to "/in" or anything. Just check the latest screenshot and you know the movie, just jump in and guess.
To make a guess at naming the movie, use the format
I'm not going to make any "Only one guess for every x hours" rule because my schedule can be erratic and I may not update on time. So I'll say that during one movie cycle, you can't guess a second time until three guesses have been made after you.
BipolarChemist made a list of movies done so far here.
Point System: There are 100 points available at any one time. Since we've done over 100 movies, points awarded are taken from whoever got the point 100 movies ago. That way the scoreboard stays dynamic.