A Bioware masterpiece
Mass Effect 2 feels like a very personal game, it makes you care about your crew members by having amazing dialogue options and writing, with so really great voice acting for a video game at its time.
You start right after the end of the first game, and some things go wrong, making Sherpard go into a coma for 2 years. When he wakes up, he discovers that the people who saved him are from Cerberus, which is a independent company who were kind of one of the bad guys in the first game. But they have a reason and try to convince him to join the cause. It's up to the player to decide how to move on from there.
The game has the classic Bioware relantionship system, basically changing from a good decision, a bad one and one just in the middle. At least most of the times, making you improve your Paragon or Renegade rating, unlocking new conversation options, for better or worse, and changing the narrative based on your decisions. What Mass Effect 2 has above the other games is the sense that you can really get to know your crew members, you can just walk around the ship and talk to them, and those dialogues have a meaning, plus, can build relationships, including romance options.
The change that enhances this the most is that you know have a loyalty mission for each of the characters you can recruit to your party. That boosts their relantionship with you and can unlock new dialogue options, as well as new skills for you to unlock for them to use in battle. It has a very traditional RPG system, you go through the missions earning XP, level up and using experience points can unlock/improve new abilities for you and your crew members. You have the option to either do it yourself or let the game auto-distribute this points.
You can also customize loadouts, each characters has a specialty, giving them a number or skills to choose from, but also, limiting the variety of weapons they are able to use. For instance, a Krogan who is a beefy heavy hiter will likely be able to use a shotgun and have good shield defenses, but a skinny Salarian scientist won't, he will have lighter weapons and offensive spells.
The game makes you really value the resources you have. It has a system where you can go to a planet, scan it for resources and then drop pods on the locations with the most amount of material, so they can transfer that resource to your party. You will use those resources to upgrade weapons, armor, your ship, your party members biotic powers and things like that, in Normandys lab.
Mass Effect 2 is a powerful game, setting a high standart when it comes to story telling for a middle of the trilogy game. It's remarkable, and the impact it puts on the players decisions, having alot of possible endings, it's just amazing to see it play out and be so well done. Even with the simple sound of a description of: "third-person cover based shooter with heavy RPG elements". I can say the gameplay holds up, even tho the story is the main thing, you'll definitely have lots of fun playing this game. It's a must play for any RPG fan out there, the best game from Bioware, in my book.