There are so many different factors to consider when doing a game review, but often what is written or spoke about is what is noticeable. Either something was out of the ordinary in a good or bad way, or implemented a known mechanic well. However, I think there are certain things in reviews that get overlooked and can lead to unintentional game review bias. I have a few that I think get overlooked, but there are likely more.
The first, and probably the one that has the most effect, is what difficulty a reviewer is playing a game on. Some games, like most in the Final Fantasy series, don't have the option to change the difficulty so there is no worry about any kind of bias as the game is being played as intended.
However, many games do have some kind of difficulty selection. Some do simple things, like increase enemy health/damage, etc. But others can get a little more intricate, like the Halo series for example. Games like Halo, can vary greatly depending on the chosen difficulty. Sometimes enemies will change in an area, what weapons they use, their AI, and a host of other things.
Looking at difficulty in that light, one can understand how playing on one difficulty over another may change one's view of a game. This is relevant because in many ways valid criticism of a game may be that it wasn't engaging enough (aka too easy) to hold your attention, or on the other side, the game set up difficulty barriers that became nothing but frustrating.
The same could be said for poorly implemented difficulty systems. Take a look at the Call of Duty series. Playing that on the Regular difficulty and the Veteran difficulty are two different experiences. Everyone who was played most Call of Duty games on Veteran, particularly World at War, knows that it is nothing but grenade spam in your general direction. If a reviewer played that game on that difficulty, their view of the game may be incredibly different.
That is not to say that their criticism is invalid, but to the overall game it is definitely biased. I would argue that the criticism of the game they have, which stems largely from what difficulty they choose, should be limited to the poorly implemented difficulty system - not necessarily the game as a whole.
Another area of unintended bias may be through the tool a reviewer used to play the game. By that I mean, did the reviewer use a keyboard and mouse? Controller? Was it an off-brand or custom controller?
Like with difficulty, it is hard to tell how big of an effect that has on an individual review, but one must assume there is some effect. For example, play Super Meat Boy with a controller and then with a keyboard. The two experiences are entirely different, and the keyboard, as it is less precise, makes it actually more difficult - at least for most people.
At the very least it is something to consider as what physically connects you to the game may have an effect on your view of it.
The final thing to look at is game presentation. By that I mean how are you playing the game? Is it at the right FPS? On an old CRT TV or a new LCD? Are you playing it at a high or low resolution? What FoV (field of view) are you playing it at?
All of those have some kind of effect on your interpretation of a game and developers do create a game with a particular presentation in mind. Viewing something at a 4:3 ratio vs a 16:9 will give you a different experience. The same can be said for FoV, as it literally changes what you can see on your screen and what you can't, which can have a reasonably large effect on a game you play. For example, for an FPS game, a low FoV may reveal an enemy to you much later, where a higher FoV will allow you to see it much earlier.
Of course you could criticize a game for allowing such variability of gameplay based on settings, but the fact remains that what kind of video settings or TV/monitor you play a game on can greatly effect your experience.
Compare it to movies. Movie theaters get detailed instructions on how a particular movie is to be presented. Things like brightness, sound levels, aspect ratio, and a host of other things. Regardless of what is being presented, the group/person that created the game or movie intended some kind of particular presentation. Obviously it is not only impossible, but unreasonable to expect everyone to experience a game in precisely the same way, but it should still be recognized that some of the creator's original intention may be lost in translation based on those presentation changes.
I may be making a bigger deal out of these things than they deserve, but I think it is still valuable to recognize that there are seemingly insignificant things that can have a big impact on a way a game is reviewed. Unintentional game review bias may not be a rampant problem, but awareness of factors that may lead to more accurate reviews as there are some games that are made to be played in a particular way. Like the Super Meat Boy example, it was designed with a controller in mind, not a keyboard.
Do you have any ideas of some factors that get overlooked in gaming leading to game review bias? Leave them in the comments!