When speaking to other characters in the game, you control the conversation via a "dialogue wheel". While some aspects from Mass Effect have been modified for Mass Effect 2, the awesome dialogue system remains the same. That interactive story is the meat of this game, and you will be spending a generous portion of your playtime engaged in dialogue. The interactive story is so rich that if you go back to number one only after finding out how engrossing number two is, you will loose out on some of the experience - factors such as the urgency and magnitude of your mission and the emotional attachment to returning characters are undoubtedly heavily enhanced by an existing knowledge of events and more importantly nostalgia. While this game could absolutely be enjoyed greatly without knowledge of it's predecessor, I strongly recommend only playing them in sequence. I won't daly too much more on the background of the game as most of that really should be learnt by playing the original Mass Effect ( AusGamers Review (9.0)).
The whole thing is very well executed and manages to push the story along rapidly without you losing any control of your player's actions and decisions in the interim. This makes room for the construction of a fresh roster of interesting characters while also paving the way for a bunch of touching reunions with old friends. Without spoiling anything (this all happens in the first minutes of play), the game freshens up the scene quite cleverly by kicking events forward two years - all your original crew thinking you're dead and gone for good. As a human, your species is still relatively new to the whole intergalactic cooperation thing, but it's up to you suit-up for humanity and save the worlds. An incredibly powerful alien force is threatening the entire Galaxy and the many sentient species that dwell within it. The sequel once again sees you filling the space-boots of Commander Shepard, a character now galactically renowned from the efforts in the first game and the story initially kicks off right where you left off. From the RPG side, it takes player character progression with currency-driven upgrades, an epic Universe with intricate lore, extraordinarily fleshed out characters with hours of fully voiced dialogue and from the shooter side it takes action-packed gun battles against dozens of enemies, a variety of weapons all suitable for different circumstances and of course, real-time combat.
Mass Effect 2 once again takes the form of a traditional role-playing videogame (RPG) mixed with a third-person shooter in an original galactic sci-fi setting. With that in mind, it makes it all the sweeter that even after being scooped up by Electronic Arts, the mighty BioWare have continued to make good on their word and delivered a worthy sequel in Mass Effect 2. Delays can blow out and even the greatest development studios can fall apart if they have even a short bad run or lose key team members - especially ones who are owned by a major publisher. In the games industry though, it's generally safer to take long-term promises with a grain of salt. A believable task given the expected longevity of this generation's tech.
When the original Mass Effect was announced for Xbox 360, it was promised as a trilogy - aiming to span the expected life-cycle of the console.