Some aspects weight more when calculating the final rating. These are predetermined constants and work the following way:

• x4 weight: Gameplay, Atmosphere
• x3 weight: Visuals, Story
• x2 weight: Characters, Audio
• x1 weight: Replayability

Of course according to the genre, budget and the aims of a game, some of these values should vary. This is something that might be implemented in the future.
For now if a category is absolutely irrelevant in the context of a game, you can give a 0 for that aspect, as 0 values are ignored while calculating overall ratings.
The meanings of the aspects are the following:

• Gameplay: basically everything that is related to the feeling of controlling and playing the game. Level and mission design also falls into this category.
• Atmosphere: the artstyle, the enviroment, how much the game can make you part of it with its consistent details
• Visuals: graphical complexity, mostly aims to represent how realitic graphics are, therefore usually a high rating for AAA games
• Story: speaks for itself, lore complexity and stroytelling
• Characters: represents how interesting characters are in the game, and how they change as the story progresses
• Audio: audio design, sound effects, music, voice acting, and how these are used to build the atmosphere
• Replayability: represents how likely it is that you will play the game again in a few years, or if there is a repetative, but fun gameplay loop (rougelikes), or if there are alternative challange gamemodes that players are likely to spend some time with after the main story

You can very easily create your own reviews by registrating with a Google account and navigating to the user "Dashboard".
While creating a review you must write the title correctly!
This is important because otherwise it is going to be registered for a separate, "new" game.
You can edit and delete your reviews by toggling edit mode on the "Dashboard".