During the most recent "Discovery & Exploration" video one of the developers mentioned that Mass Effect: Andromeda will have less planets to explore than the previous games, but that they will be much more detailed than ever before. While the following hasn't been confirmed just yet, it appears there will be seven main planets for us to roam around in, the so called "golden worlds" that are capable of supporting colonists. Chances are there will be more planets out there, but I think its a safe bet to say that these seven will represent the majority of our playtime in Andromeda.
If you're wondering what these golden worlds might look like you'll find the recently posted video down below. And don't worry about spoilers as the video only covers the most basic information and lore, so feel free to indulge your curiosity! Anyway, have a look:
On the other hand, if you would like to learn more about the actual gameplay in Mass Effect: Andromeda, you can find the very first gameplay preview by heading over here. It features a brief overview of all the basic weapons and combat mechanics, skills and their effects, as well as a couple of the enemies you'll get to smash into the ground. And if you would like to delve even further into the combat system you'll find the second preview video right here. This one is focused around squad based tactics, player skill and weapon profiles, as well as gameplay variety. Enjoy!