So I have 1300 games on Steam. I've played most of them, and I've read Steam user reviews for all of them. Here's my quick interpretation of what the user review scores mean when there are at least 1000 user reviews.
NOTE: It's important to note that games generally review much better than they deserve and that many people who don't like a game will nevertheless leave a positive review because they believe other people will enjoy the game, or they just don't like leaving negative reviews.
95% to 100% Positive (Overwhelmingly Positive)
If you like games in this genre, you are almost guaranteed to like this game. This is as good as it gets. Almost perfect.
90% to 94% Positive (Very Positive)
If you like games in this genre, you are almost guaranteed to like this game. A small number of people may dislike a system in the game that spoils the experience for them, but it is overall a great game. It is probably worth your time to read the negative reviews, but I would only pay attention to problems mentioned by more than one reviewer.
80% to 89% Positive (Very Positive)
If you like games in this genre, you will probably like this game. There are some minor problems with the game that some gamers will find too much to deal with. You should read the negative reviews to get a better idea of the problems. Look especially for things that more than one person mention.
70% to 79% Positive (Mostly Positive)
It's a coin toss whether you will like this game or not. Proceed with caution. There are numerous things about this game that people don't like. Carefully read the negative reviews, especially noting items that are mentioned by more than one reviewer.
69% and below (For AAA games only)
You are probably not going to like this game, but it is still worth your time to do the research. Read both positive and negative reviews. Sometimes the positive reviews may provide perspective on the negative reviews. For AAA games, often the games just aren't good, but other times, games that don't quite meet expectations can end up here, and the negative reviews can snowball and make a game seem worse than it really is. If this is a genre or series that you really love, it is possible that you may still enjoy this game.
69% and below (For Indie games only)
You are very unlikely to enjoy this game. There are numerous problems with the game, some very serious. If you do research on this game, realize that there could be, and probably are, problems that the reviews fail to mention. Only consider purchasing this game if it is extremely cheap, and you love the genre.
Would be interested in hearing other people's takes on how to interpret user reviews.
NOTE: It's important to note that games generally review much better than they deserve and that many people who don't like a game will nevertheless leave a positive review because they believe other people will enjoy the game, or they just don't like leaving negative reviews.
95% to 100% Positive (Overwhelmingly Positive)
If you like games in this genre, you are almost guaranteed to like this game. This is as good as it gets. Almost perfect.
90% to 94% Positive (Very Positive)
If you like games in this genre, you are almost guaranteed to like this game. A small number of people may dislike a system in the game that spoils the experience for them, but it is overall a great game. It is probably worth your time to read the negative reviews, but I would only pay attention to problems mentioned by more than one reviewer.
80% to 89% Positive (Very Positive)
If you like games in this genre, you will probably like this game. There are some minor problems with the game that some gamers will find too much to deal with. You should read the negative reviews to get a better idea of the problems. Look especially for things that more than one person mention.
70% to 79% Positive (Mostly Positive)
It's a coin toss whether you will like this game or not. Proceed with caution. There are numerous things about this game that people don't like. Carefully read the negative reviews, especially noting items that are mentioned by more than one reviewer.
69% and below (For AAA games only)
You are probably not going to like this game, but it is still worth your time to do the research. Read both positive and negative reviews. Sometimes the positive reviews may provide perspective on the negative reviews. For AAA games, often the games just aren't good, but other times, games that don't quite meet expectations can end up here, and the negative reviews can snowball and make a game seem worse than it really is. If this is a genre or series that you really love, it is possible that you may still enjoy this game.
69% and below (For Indie games only)
You are very unlikely to enjoy this game. There are numerous problems with the game, some very serious. If you do research on this game, realize that there could be, and probably are, problems that the reviews fail to mention. Only consider purchasing this game if it is extremely cheap, and you love the genre.
Would be interested in hearing other people's takes on how to interpret user reviews.