You can only do a review on a specific game, not a game series. If there are two parts to a game, like some of the FF series, you can do the whole thing, but not for, say, different Zelda games. The topic of your review MUST be the name of the specific game you're talking about.

Try to include at least the following genres; you can add more if you want (leave out multiplayer if it's not there):

Gameplay: Fun factor of a game
Controls: Tell how the game plays in terms of the controller
Visuals: good? bad? totally balls to walls suck?
Audio: very good (Halo 2), totally shitty (Big Rigs)
Replayability: Is it fun enough to be replayable?
Multiplayer: is there any and/or would it make the game better if it had some but doesnt

Also, if you want to see direct feedback from the population, you should make a poll from 1 to 10, 1 being the worst, 10 being the best, so people can vote according to how they think it is.

Please make your reviews a good length, more than a paragraph would be nice. Also look at different categories and discuss them as fully as you can, not just one category. Individual scores for each category is not required, but an overall score from you would be nice to hear.