"When aliens misinterpret video feeds of classic arcade games as a declaration of war, they attack the Earth in the form of the video games." 
At first I didn't want to watch this movie, because I'm not really a fan of comedies, but this was also sci-fi and contained arcade games. And I thought that I might like it, considering I loved Wreck-It-Ralph.
And I was right. Yes, there were some stupid moments, but all in all, I enjoyed the movie immensly. The basic plot is that the 1982 arcade game championship is filmed and then the footage is send to the space where it is found by aliens that consider it a declaration of war.
They come to attack earth some 20 or so years later. I'm not entirely sure what 'present' year it takes place in, but I'm guesssing that around 20-30 years passed from the championship.
A group of people, that are good at arcade games, or were, band together under the president, who used to be an arcade gamer too, though not that good, and they fight the aliens who re-create the arcade games in real life.
The movie is full of fun as well as intense moments and while I'm not a big fan of comedies, I am all for some fun and I think that this 'comedy' didn't overdo it with the fun and that's good.
The main characters are played by Adam Sandler, Kevin James, Michelle Monaghan, Peter Dinklage and Josh Gad.
The guy who played Boromir, Sean Bean, also makes an appearance. Not a big one, but one non the less and that was actually the main reason I watched the movie. Though in the end I enjoyed it regardless of Sean Bean.
The one actor that I didn't like was Peter Dinklage, but not because of his acting skills, I think he's a good actor, but I just don't like the characters he playes. First it's Trask in X-men, now this little cheating twit. Sure, his acting is good, but the characters he playes make me not like him.
I would definitely recommend the movie, but I would also say that it is not a movie for everyone. If you like crack-ish sci-fy, you will definitely like this. If you don't, you might still like it, but it is not guaranteed.
The one thing I do when picking what movie to watch, I go by the people who play in them. If a favourite actor plays in it, I usually watch it without checking either the summary or anything else.
Most of the times it works. Unless we go by My Bloody Valentine, where I started watching and then I got curiious and went and googled who the murderer was before the movie ended and got angry that it was the actor because of whom I was watching the movie, who was the bad guy that I turned the movie off without finishing it. From that moment on, I decided that I would never look things up before actually finishing whatever it is I'm watching.
Not that that did me any good considering I did the same bloody thing with Prison Break, only there, I went and googled who of my favourite characters will survive. Again, stopped watching because of the answer I got.