To date, Mass Effect is the only 360 game for which I have collected all available achievements. I have completed it four or five times playing as different classes and backgrounds, taking different team-mates, on different difficulty settings, and making different decisions. I even bought and completed both the DLC add-ons, not realising what a massive rip-off they would prove to be. I love Mass Effect because it plays out as a crisp, non-linear action-RPG, but in a reassuringly familiar setting that taps into my love of nerdy space adventures.

There was never any doubt that I would buy Mass Effect 2 as soon as it came out and go absolutely crazy playing it over and over again. The strange thing was that, because Mass Effect is both quite long and highly replayable, I was never particularly bothered about when that day would come – whenever I got the urge to dive back into that universe, I would just start a new game and look for new things to try. Two years on, the sequel appeared almost before I was ready, prompting a last-minute dash to level 60 and that final achievement. I probably could have kept playing for another year before I got bored of it. Still, the sequel is out, and most obsessive fans will have finished it at least twice by now. I myself am currently 70% through my second play-through, wading through ‘Insane’ mode and figuring out all the bare knuckle combat exploits that just aren’t necessary at lower difficulties.

I get the feeling that most of the gameplay changes have been directly shaped by player feedback from the original game. The sequel feels a lot more linear, possibly as a part of the general trend to stop hiding content from players – which was certainly a major element in Mass Effect. Your ultimate objective, outlined at the start of the game, is to travel through a quarantined mass relay into an unexplored region of space and shut down an alien plot to abduct human colonies, and this never really develops much over the course of the game. Most of the plot and intrigue occurs during the 40-odd hours you spend preparing for this final attack – recruiting team members, earning their trust, upgrading your ship, and investigating the aliens responsible for the abduction.

It seems strange that Bioware would build the game around such a straightforward, almost entirely twist-free central plot. One of the best things about the original game was that its modular story would adapt itself around your chosen route through the game – the four main missions each contained a vital piece of information, all of which must be combined in order to locate the Big Bad’s secret base and take the fight to him. In Mass Effect 2 you just seem to fly around the universe ticking off items from a shopping list, with sudden spurts of deus ex machina shunting the story along when you reach certain milestones. It’s a bit disappointing really.

Similarly, the side-missions and planetary exploration gameplay have been streamlined into a much simpler format. I know a lot of people complained about how many hours were spent driving around barren landscapes in the Mako, but I was surprised to find it completely absent in the sequel. The boring, pointless task of surveying mineral deposits now takes place through an equally boring and pointless scanning probe minigame played in orbit, while the planets you can land on have been transformed into linear romps down fenced-off trails. This allows a much greater degree of directive control over the mission and its environment – certainly a big improvement over the featureless moons and identikit warehouses that plagued the original – but you do lose some possibilities for interesting missions, such as on the planet of the space monkeys.

Plot missions are shorter in the sequel, but much greater in number. Most are recruitment missions, which involve going to a city, finding someone who can tell you how to find the person you’re looking for, then travelling to a linear combat area and killing whatever group(s) of people are preventing them from leaving. Each crew member comes with an optional ‘loyalty mission’ that unlocks a new, Cerberus-themed outfit and a unique bonus skill; these usually involve another linear killing spree, then an interesting scene in which your crewmate’s dark secrets are revealed, and then a final conversation where you choose whether or not to allow them to kill some figure from their past. The stories that unfold during these loyalty missions lead to the most interesting moments in the game, which do make up for the repetitive mission structure, but in some cases it leaves you feeling like the combat is an arbitrary chore they wedged into the mission just to swallow up your time and effort, so that it feels like more of an achievement when you reach the end.

All of this sounds a bit bleak and boring, but the bulk of Mass Effect 2‘s gameplay is a great improvement over its predecessor. The bloated inventory system has been almost entirely removed and replaced with an armour customisation system that is brilliantly designed but slightly underwhelming in terms of options. The skill system has been simplified, although the range of skills available has greatly increased. The biggest improvements are found in combat, where weapons and skills now enjoy varying efficacy against health, armour, shields and biotic barriers. ‘Thermal clips’ restrict how much ammo you can carry, invariably not quite as much as you’d like to, which encourages you to switch between weapons and vary your strategies much more.

It’s just a shame that they couldn’t make these improvements without delivering a such a weakened narrative. One of Mass Effect 2‘s talking points is that anyone and everyone in your crew, including your character, can be permanently killed at certain points of the game, but most of these deaths feel really random and undeserved – it doesn’t come close to the drama of Mass Effect‘s Virmire mission. The closing cut-scenes include some pretty big hints about what is to come in Mass Effect 3, and it looks brilliant… unfortunately, it comes across as a slap in the face when 10 seconds of CGI is more exciting than the 40 hours of game you have to play through in order to see it.

I suspect that Mass Effect 2 will eventually be remembered as the weak link in the trilogy. It’s a great game, but it feels like filler material – a public playtest of new combat mechanics, in preparation for a show-stopping second sequel.