Final Fantasy XV is an action RPG developed by Square Enix and is not connected to the previous installments of the series.
The story takes place in a world of Eos. Noctis Lucis Caelum, the heir of the Lucis Empire throne sets out on a quest with his comrades in order to recover a stolen magical gem the theft of which sparks a global conflict between all the nations in Eos.
The combat system resembles the same one featured in Final Fantasy Type-0 but is heavily modified. There is no option to control any of the four main protagonists apart from Noctis himself, yet it is possible to command your teammates. It is possible for the players to use vehicles such as tanks or robots or summon beings that differ in rank based on their size. There are no battle-specific battle screens in FFXV.
Magic is also present in the game. By consuming the power of natural elements from their sources, Noctis is able to cast spells. The Protagonists have the ability called Link Form which allows for contextual attacks.
The main emphasis is put on the road trip with your friends. FFXV features a massive open world which can be freely explored. Dynamic day-night cycle and weather systems are also present.
Much like just about every Final Fantasy game since FFX, XV fails to meet the expectations that fans had built during the absurdly long development process for this game. That being said, there is a lot to love here. Probably the biggest achievement is how much fun I had level-grinding. The game is at its best when you're marathoning side-missions for two-to-three days with no sleep, driving to new corners of the map in your monster truck Regalia, carefully planning out where you're going to stop to eat and stop to sleep so you can max out your EXP for level-ups. It's really simple, but really rewarding, and at the end of the day that has to do with strong gameplay, strong characters, and strong world-building, all things that can be said of the best Final Fantasy entries.
Side note: haven't played the most up-to-date version of the game, so I'm curious how much the changes to the story actually affect my overall enjoyment -- probably won't get around to playing it for a long time though.
I've replayed this at least 3 times but after the last playthrough and purchasing the full edition I have to say this is pretty terrible. Broken story, terrible combat, amazing graphics. Skip this and play the classic Final Fantasies.