There is no prescribed format. You get to make it up to be the review you want it to be -- personally I go with writing the review I would want to read (trying to do something in another's style rarely works, and honesty goes without saying*), though if you can make it a bit more wide appeal then do that (I rarely find online multiplayer that compelling but I reckon I can give an assessment of the quality if the single player is something I am otherwise looking at).
Most would suggest you break it up into sections (5000 words is a long thing for a single essay, broken up into sections of a few paragraphs and it is far more approachable for many), pictures are nice, intro/overview followed by meat and conclusion is tried and tested, some kind of humour often works but can have downsides (especially if you fluff the humour).
*ape someone else's style and most will consider it finding your groove after you crank out a few good ones, misunderstand a mechanic resulting in your dissing an otherwise good game and again a few good ones and water under the bridge, once a shill or a liar then forever a shill or a liar.