How Do I Know If A Game Is Worth Downloading?

I'm currently using a star rating system where i give my opinion about the games that i post

: I did not like it
: It was ok, but not that great
: Worth a download, killed a few hours
: Great game, definitely download.
: YOU MUST HAVE IT!!!

Do remember that this is my opinion on the games, if there is a game that i said that is 5 star and you did not like its entirely acceptable, so this happens in any ways like if i said I did not like this game and you loved it and vice-versa.