The Gameplay section is a crucial component of a good video game article. Although it may be relatively easy for an experienced gamer to write such a section, care must be taken to maintain an appropriate focus and balance. The section should be written for readers with little or no knowledge of video gaming and should not be filled with detailed information about weapons, levels, or other such topics that are only of interest to the video gamer or that might be found in a game guide. Your goal for crafting a good section is to have people who have never picked up the game understand the basic mechanics. Do note, however, that it's safe to assume the reader has at least a minor knowledge of what a video game is.
This section often begins the body text after the lead, but is sometimes placed after the Plot section. Games with little or no story can cover the plot in the Gameplay section. When writing about a game, use your head and common sense about the ordering. Generally, start off with a broad stroke—is the game a RTS or an FPS, etc. Don't talk about why the gameplay is like it is; generally, that is better placed in the 'Development' section later on in the article.
Images can be added to better illustrate some aspects of gameplay. Generally, a single screenshot will suffice. Because of screenshots are non-free content, usage should be minimalised. Multiple images can be used, but all images should add something to the article beyond what the prose states. All non-free images require a fair use rationale to be used on Wikipedia.
Things to remember
Don't add in cruft about weapons, levels, and minute details of trivia; gameplay sections should serve as a primer to the game, not an exhaustive list of every facet of the game.
Don't use gaming jargon which can be confusing to readers, such as "NPC" or "MMORPG". If you use these terms, state the full name and the abbreviation the first time it appears. For example, "Halo is a first-person shooter, or FPS."
Wikilink! So you don't have to describe what a god game is, link it.
Talk about what makes the game different from others; if you only talk about why StarCraft is a real-time strategy game, then readers could just visit the article about the game genre and be better served.