In all of the Final Fantasy Games, there are many similarities:
- Chocobo (Since FF2)
- Spells like "Holy", "Meteor", and "Ultima"
- Excalibur and Masamune
- Summons - Bahamut, Ifrit and Shiva being the most common recurring ones.
Obviously, some of these Themes are a bit ambiguous - any fantasy game deals with magic and summoning, and Excalibur are used throughout any Fantasy medium. However, these recurring themes have been in (almost) every single Final Fantasy game to date.
So is there any kind of ties between the games? Whether they simply exist in the same timeline, however far apart, or are just alternate versions of the same universe?