The trailer is cool but the best stuff comes from the GI issue, loads of info. Dream game coming!

Backstory
-Around 2185, at the height of galactic progress, unaware of the impending Reaper invasion (though after Sovereign), several species band together for the "Andromeda Initiative"
-4 Arks, each carrying a different race, are built, housing thousands of individuals to chart a course to Andromeda

More on the Andromeda Initiative:
"Founded in 2176 and launched in 2185, the Andromeda Initiative is a civilian, multi-species project created to send scientists, explorers and colonists on a one-way trip to settle in the Andromeda Galaxy. With powerful benefactors lending their support, the program has grown substantially in scope since its inception. The Initiative’s ultimate goal is to establish a permanent presence on the seemingly resource-rich frontier of Andromeda, and eventually create a reliable route between it and the Milky Way Galaxy."

-Turians are confirmed in the game
-The Heleus Cluster is noted as having a significant amount of "Golden Worlds", or planets ripe for life
-Each ark is led by a "Pathfinder"
-The Pathfinder, recon teams and others onboard are in cryosleep, unaware of what transpires in the Milky Way after they depart
-You play as either Scott or Sara Ryder, the children of Alec Ryder (pathfinder of the human ark)
-Alec Ryder is voiced by Clancy Brown
-Events at the start of the game occur that pass this role down to you, you are untested and unproven, unlike Commander Shepard of the previous trilogy
-This doesn't mean Mass Effect is Ryder's story from now on, they want the game to feel like a complete story (while teasing other stories that could happen)
-More customization options than previous games
-You can customize your father and your sibling, though not as extensively
-The "Nexus" is basically a forward command center staffed by multiple species that arrives in Andromeda early to pave the way for the Arks
-The Hyperion (humanity's ark) arrives at an incorrect location that's volatile and loses contact with the other arks and Nexus

Inspiration
-The (much improved) Mako of ME1, the loyalty missions of ME2, the multiplayer of ME3

Combat
-Global cooldowns are now replaced by individual timers
-Powers are instead hotkeyed for quick use, no longer pausing to bring up a wheel and aim (you can still pause the combat but it's not how BioWare intends combat to function)
-Dynamic cover system (ala TLOU)
-Still a cover based shooter with a goal to get the player moving around the battlefield more
-Jetpack allows for more movement variety; you can quick dash instead of rolling
-Jetpack has a hover function that allows you to hit enemies seeking cover or survey your surroundings
-Less emphasis on linear, clearly telegraphed environments that tell you a combat encounter is coming (though linear areas are still in the game)
-Game Informer's hands on was positive, feel the game has a clearer identity in combat than previous games
-You still queue up attacks, combos, order your squad, etc
-All key elements are still intact but the studio wanted to encourage more experimentation and wider variety of abilities

-Class system is gone; instead you have full access to abilities from all classes, you can mix and match skills from tech, soldier or biotics
-Goal is to allow players to try different approaches to combat without being locked in at the start
-However, you can still specialize once you invest enough points into a category of skills, you unlock a profile that can get you bonuses for your particular play style
-This is where class names like "Vanguard" (invest in combat and biotics) and "Adept" (invest in biotics) resurface
-Invest in multiple categories and you unlock the "Explorer" profile
-There is a narrative reason that allows you to reconfigure your points throughout the game so that you can try out multiple gameplay approaches without making multiple characters
-You can customize your helmet, chest, shoulders, arms and legs, more extensive than previous trilogy
-Many familiar weapons return, as well as new melee options like swords and hammers

Enemy/Environments/Crafting
-The 'Kett' are the main enemy
-The team wanted players to experience the first time encountering a new alien species vs already having it established in prior games
-Rather than painting them as mortal enemies, BioWare wanted to make them feel foreboding but not ugly as they want you to also empathize with them
-Instead of having "linear slices" of planets that you land on, you explore these planets from the surface to their underbelly
-Critical paths, optional planets, major hubs, loyalty missions return
-Your land vehicle is designated the "Nomad", and the team got special guidance from NFS developers on its handling.
-The Nomad isn't sluggish and cumbersome like the Mako, it's very fast, still boosts and maneuvers much better
-The Nomad doesn't have weapons, you can customize things like its speed and appearance
-BioWare did not want to repeat having things like mineral nodes and multiple identical outposts scattered across planets
-Points of interest include combat encounters, puzzles, narrative beats etc on planets
-One planet, called 'Elaaden', is flagged as a possible habitat zone, however the surface is hazardous (no water, extremely hot); you can be pointed in this direction in multiple ways, for example, a Krogan can request the Pathfinder to find a missing colony ship or you can just choose to land on the planet yourself and see what you find
-On planets, one of your priorities is to scout for drop zones for your crew that drop "forward stations" that establishes a foothold for you
-These stations allow for changing up your loadout, fast travel point, etc
-Planets can have multiple dangers like acid pools, burning wreckage, weather etc that can all kill you
-Most planets have at least one major enemy base
-Planets can have areas, encounters and "super bosses" that are too tough for you to handle at first, encouraging players to come back later
-Since Andromeda is a new galaxy, Ryder can actively scan and discover things in the environments; that gets sent back for analysis and unlocks new technologies for the player
-Scanning and discovering these things also allows you to obtain blueprints to craft weapons and armor for yourself
-You can create a wide array of items, not just ammo types and weapon mods, items that haven't been seen before in the Milky Way (thanks to new alien tech)
-Some plot threads and missions lead you across multiple planets

Squadmates
-Peebee (nickname): Asari squadmate shown in previous footage. Went off on her own after arriving on the Nexus and described as having a "bubbly personality". She's smart and not concerned with social norms and "niceties".
-Liam: Arrived with the Pathfinder, former police officer and described as having a "light attitude", bringing levity to situations

The Tempest (Your Ship)
-Important to harken back to the Normandy as it was a fan favorite
-There are no loading screens as you move through the ship
-Galaxy map returns but rather than piloting a mini ship on a map, it is more immersive, you select a planet, the game gives you sense of traveling towards that planet, and when you back out, you're immediately at your destination
-You don't pilot the ship manually, but it feels seamless as you go from planet to planet and see them from your bridge getting closer in the window
-They wanted a seamless experience from picking a planet to walking down to your cargo hold, hopping into the Nomad and landing on a planet. There is a landing sequence and you get off the ship. No more loading screens and instantly popping up on the surface of a planet.

Relationships/Characters
-There are more relationships in the game than any other Bioware game (as they noted fans make a big emphasis on romance in the games)
-The squadmate with the least amount of lines in Andromeda has more lines than the squadmate with the most amount of lines in ME3
-Due to complications in the awakening process, your sibling won't join you in combat but you can interact with them and build a relationship
-Many of these dealings are optional, and discovering more about the Ryder family is a plot thread
-BioWare is confident the details of this story are what differentiates it from a traditional "hero's journey"
-Loyalty missions return but they are not critical to the ending of the game; you can complete them after you complete the main story path for example
-Emphasis that relationships don't just culminate in a sex scene, but rather characters can just want to get in the sack, while others are interested in long term relationships and others still aren't interested at all. Bioware wanted to capture more "shooting bottles with Garrus" moments in the game, of which there are plenty

Multiplayer
-More evolved and refined form of ME3
-Card based economy where you earn XP and credits
-There are microtransactions but no real world money is required, you can unlock normally
-You still set the map, enemy, as before but you can also activate modifiers that can give you decreased health (for greater reward) or more damage (less reward)
-Bioware also plans to release custom crafted missions with unique modifiers that players can't change themselves
-These custom missions give you a 3rd currency, "mission funds" which allow you directly purchase items and weapons vs the mercy of random card packs; however these items are only available for a limited time in the store and can change often
-In MP, you play as the "Apex Force", a militia strike team from the Nexus
-Different enemies require you to use different tactics (some are shield heavy, some use heavy biotics etc)
-Playing MP will have advantages for the single player but it absolutely does not affect the ending of the game
-New "Prestige" mechanic added: With several types of characters, you earn regular XP and prestige XP. The prestige XP goes into every character of that 'type', for example 'tanky' characters. Earning enough prestige can grant you added health for all tank characters, etc.

Choices
-No more Paragon/Renegade system
-They want more nuance and subtlety and giving the player more opportunity to express themselves
-You can agree or disagree with someone without being punished or cornered into a paragon or renegade choice
-Dialogue option tones: heart, head, professional and casual.
-These don't affect you or sway a meter one way or another, rather they allow you freedom without worrying about unintended consequences
-"Narrative actions" (previously "interrupts) return but rather than giving a "red"=bad or "blue"=good choice, it can say "shoot", leaving more ambiguity to your choice
-Decisions aren't necessarily obvious "right" or "wrong", there are pros and cons to each and you'll just have to play the game the way you want

The future
-Mass Effect: Andromeda leaves the door open for more games (obviously)
-New game+ mode allows you to change your gender if you choose
-BioWare is coy about multiple endings; "it's a suprise", "it's different than the trilogy"

Exploration is the only thing holding ME from a 10 for me. If this game has interesting areas to explore and the secrets and optional stuff has good gameplay it could be one of the greatest games ever made. I cannot wait.

So did the arks leave expecting to find alien life in the Andromeda system?  Because if so, taking 600 years to get there would be a huge risk.  Also, why would you separate the different species by placing all individuals of the same species on one ark?  Not really a good basis for interracial cooperation.