The sequel is incredibly tricky to nail, and only a select few manage to exceed the original.

The original 'Mass Effect' launched in 2007 to strong reviews and sales, but it was seen as a merely very good game instead of great.

There was definitive room for improvement from the original, with an underdeveloped squad-based combat loop, vehicle controls that felt like controlling a shopping trolley with the wheels missing and apart from one major choice in the second act, the choice system didn't drastically alter the gameplay.

'Mass Effect' is still a triumph of writing, but there was scope for improvement when it came time for the sequel, and 'Mass Effect 2' very well can lay claim to being the greatest video game sequel of all time.

In the simplest terms, 'Mass Effect 2' is the 'Empire Strikes Back' to the originals 'A New Hope'.

We've talked about sequels in this series of articles, but 'Mass Effect 2' can hold a legitimate claim to being the greatest gaming sequel of all time.

Back in action

The opening 15 minutes of 'Mass Effect 2' is as thrilling as game intros get, and similar to how 'Uncharted 2: Among Thieves' showed players the sequel wasn't messing around with it's opening set piece, 'Mass Effect 2' ups the ante for the sequel straight away.

Before you even get to create your character, Commander Shepherd is killed, and we know straight away that we are facing our greatest threat yet.

Shepherd is brought back to life by a shadowy organisation called Cerberus, and the game instantly raises an interesting moral quandary; can you really trust the people who literally brought you back from the dead?

All great sequels introduce new characters alongside characters we already know and love, and the new batch of 'Mass Effect 2' crewmates are among some of Bioware's greatest creations.

The wonderful Dr. Mordin Solus, femme fatale Miranda Lawson, wrecking ball Grunt and the remarkably unremarkable Jacob Taylor mix well with our returning buddies Joker, Garrus and Liara.

If we had to pin down why 'Mass Effect 2' feels so special, it's because it places you smack bang in the middle of an episode of 'Star Trek: The Next Generation'.

Wonderfully written characters mix with lush, beautiful worlds, and you genuinely come to care for your crewmates.

'Mass Effect 2' represents where gaming has the advantage over film and television: you can form a deep, personal relationship with fictional characters and explore worlds ripped straight from your imagination.

The 'Mass Effect' franchise appeals to the same part of the brain that makes you doodle rocket ships in your copybook in school, and in the second entry, everything meshes together into this transcendent game that is quite simply unlike anything we've played over the last 25 years.

The richness of Bioware's writing is in full effect here, with characters showing layered, complex depths, which makes it all the more depressing when you see what happened to Bioware later on in the decade when they fall into the live service trap with 'Anthem'.

At the heart of 'Mass Effect 2' is this driving question; to what end do the ends justify the means?

With Commander Shepherd killed by a deadly enemy force at the start of the game, Cerberus moves heaven and earth to bring someone back from the dead.

Making space

When Shepherd reunites with old friends from the first game in 'Mass Effect 2', they are treated in kind with distrust and unease, and this helps drive home that the world of 'Mass Effect' is not as black and white as it seems.

The main appeal of 'Mass Effect 2' is getting to know your crewmates, and without explicitly telling you, the game expects you to build up a strong relationship with your crewmates in order to survive the impossible final mission.

An unprepared player will breeze through the game without doing the loyalty missions and get a nasty surprise when your crew drops like flies in the final assault on the Collectors base.

But the master stroke of the game is you want to engage with your crewmates regardless.

Therein lies the genius of 'Mass Effect 2'.

No game puts as much effort into fleshing out the characters as 'Mass Effect 2', and as we touched upon in our retrospective piece on 'Bioshock', the HD era of gaming is when gaming really unlocked its potential as a storytelling device that trumps what Hollywood or a good book has to offer.

'Mass Effect 2' plays out like a mix between 'The Dirty Dozen', 'The A-Team', and the best episodes of 'Star Trek', and it is utterly irresistible.

Playing 'Mass Effect 2' like a paragon of virtue like Captain Picard or a space version of Dirty Harry is half the fun, and adds a great degree of replayability to the game.

If you play the game like an upstanding citizen, going out of your way to carry out good deeds and making the Paragon decisions, you can come out of the game with your moral compass intact, but if you choose to indulge the darker tendencies and become no better than Cerberus, the game becomes a fascinating philosophical debate.

If someone is brought back from the dead using cutting-edge technology and limitless money, does the soul remain intact?

By playing as an upstanding Commander Shepherd, you can prove those philosophers wrong, but if you indulge in the more evil options, you can become a truly unholy terror.

2012's 'Mass Effect 3' remains a controversial entry in the series with the game widely regarded as having a worse ending than 2019, but the problems with that game did not stem from the ending.

The stakes are dramatically upped in 'Mass Effect 3' so the game can't really justify giving you fun side quests like finding better food for the ship's kitchen, but it is the smaller moments that make 'Mass Effect 2' dense and rich.

The first time you discover Mordin has a reworked Gilbert and Sullivan musical number in his arsenal is one of the most joyous moments in gaming.

Smoke And Mirrors

We've spent the last 1000 words or so gushing about how incredible our squadmates are, but every story needs a great baddie.

'Mass Effect 2' provides not one, but two great villains for our pleasure.

Martin Sheen introduced himself to a new generation of fans thanks to his performance as The Illusive Man, with the former NUI Galway alum lending a sense of gravitas to the game.

Sheen's voice and cigar-chomping disposition makes The Illusive Man one of the great characters in all of gaming, and while we see his true motives revealed in 'Mass Effect 3', the master and servant or water and oil dynamic the player can deploy is a major part of the 'Mass Effect 2' experience.

You can call The Illusive Man out for his shady ethics and tell him that you are only carrying out his missions for a heroic cause, or you can fully embrace the dark side and become his personal lapdog.

The Illusive Man shows what could have happened if Luke Skywalker took Darth Vader's offer in 'Empire Strikes Back' of ruling the galaxy together, and the answer is it erodes your soul.

The Collectors are also worthy rivals, and the deep, booming voice telling you that they have assumed direct control never stops being creepy.

When players assume control of Joker when The Collectors board the Normandy, the game quickly loses its swashbuckling space adventure tone and turns into 'Event Horizon'.

We see up close and personal how evil The Collectors are, and seeing them kidnap your shipmates serves as a very powerful motivator.

Indeed, if you haven't completed all the loyalty quests at that stage and delay going after The Collectors to complete the loyalty quests, the auxiliary shipmates are turned into liquified goop by the time you reach them.

'Mass Effect 2' is absolutely masterful at drawing you into the game world, and it underpins just how important your choices are.

By offering players a glimpse into the dark side, 'Mass Effect 2' is a shining example of what gaming can do better than other art forms.

On the flip side, cosplaying as The Doctor or Ellen Ripley and putting differences aside to save the galaxy is as thrilling as any great sci-fi adventure.

The original 'Mass Effect' has its charms and quirks with its exploration mechanics, and 3 is the best game in the series in terms of gameplay, but for depth of story, writing, and an overall sweeping sci-fi story, it is very hard to beat 'Mass Effect 2'.