system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The plot of Final Fantasy

I've tried reading Wikipedia articles but it's very non-linear and erratic.
gpt
The FF series are almost all standalone titles. They have no larger continuity between the various entries. 
There are some exceptions, such as FFX and X-2. Also XIII,  XIII-2 and Lightning Returns. 
FF Tactics, FFXII and Vagrant Story are also part of the same universe.