The game has a story mode where you can star in your own adventure, going on side missions and exploring the world. However, you can also interact and ally with other players.
As is often the case with this type of game, the combats are done by turns. You pick the action that you want to carry out (attack, defend yourself, cast a spell, run away...) and then your enemy does the same. It's that simple and addictive.
NEStalgia is a game that will be too difficult for anyone who didn't live through the golden age of the RPGs. However, if you have a few years of experience playing these types of game you might do very well.