Not every fan of the saga goes through all the parts of "Mass Effect" in order: they usually limit themselves to the first three, because Captain Shepard's heroic odyssey is an imperishable classic. The fourth is knocked out of the canon and tells about events that fit into the time period between the end of the first and the beginning of the second part.
This will be discussed in the article.

Mass Effect
BioWare's 2007 brainchild received positive reviews due to the colorful graphics and gameplay.
The plot tells about space exploration and attempts to achieve recognition of man by other civilizations. Captain Shepard is investigating the case of the Specter Saren - he suspects connections with the ancient Reaper race.

Mass Effect 2
Sequel came out in 2010. Compared to the first part, the graphics have been improved, the game menu has been optimized, and the mechanics have been improved.
New characters have appeared, the most popular (to this day) of which is Miranda Lawson.
Reapers are notmanifest directly, but a race of Collectors has appeared who kidnap colonists to fill the mechanisms of the Proto-Scorcher.
At the end of the final cutscene, the player sees a galaxy approaching from distant space - a direct hint for a sequel.

Mass Effect 3
A dizzying battle begins on Earth - the Reapers have come to harvest organic life.
If you go through all the parts of "Mass Effect" in order, then in order to see the end: the secret of the creation of the Reapers will become known.
The developers took into account the oversights of previous releases, worked out the graphics and mechanics.

Mass Effect: Andromeda
The action takes place in parallel with the events of the second part: the player will have to go to the Helea cluster and explore habitable planets.
The game received a lot of negative reviews, the developers received negative messages and even death threats from disappointed fans.
This resulted in the end of support for the game and the cancellation of single DLC releases.

Verdict
It's not worth going through all the parts of "Mass Effect": it's enough to limit yourself to the first three. It's like reading a good book with a complete story.
Andromeda is an amateur product, inferior in quality to the previous trilogy.