Halo: Campaign Evolved is more successful at being a reinvention of an FPS classic than it is a reproduction - and that needn't be a bad thing.

When Master Chief first sets foot on the unknown ringworld known as Halo, he is fighting for his life. Harried and ambushed by countless enemy ships, Chief's commanding officer scuttles their intergalactic craft upon the ringworld - assuming the human troops will fare better on this structure than face a cold, indifferent death in the vacuum of space. But once they set foot upon Halo, they realise all is not what it seems; here, they are trespassing on the work of a culture that has come before. They are treading on the face of a masterpiece. Interfering with greatness. I can't help but see the parallels to Halo Studios and Bungie.

Halo Studios has an almost impossible task with Halo: Campaign Evolved. They are to infiltrate the world of Bungie's masterwork, and attempt to create a facsimile of it in an inferior engine, with precious few of the original developers to help steer them in the right direction. Conditions are hostile - so hostile, in fact, that even some of the architects of the original game are against Halo Studios. And yet, like one lone armoured supersolider wreaking havoc on a Covenant cruiser, Halo Industries has done something heroic here - it may not be perfect, but Campaign Evolved does manage to do the impossible: it summons the feeling of playing the original again for the first time.

Halo: Campaign Evolved - Official Reveal Trailer Here's a look at Halo: Campaign Evolved in action.Watch on YouTube

There are plenty of changes, though. You can now aim down sights on every weapon (but taking damage still descopes you, promoting mobility over camping). You can sprint (once again, promoting adaptability and momentum). There are more vehicles dotted around the maps, harkening back to the original Halo's genesis as a 'vehicular combat' strategy game. There are more weapons for you to pilfer from the battlefield, more tactical options at hand for the harder fights. There are dozens of skull modifiers. The later levels have been rethought, stripped of their tedium, packed full of interesting new mechanics.

Thanks to the series changing so much over time - the second game gave you the option to pick up an Elite's energy sword or hijack enemy vehicles, the third game introduced support weapons and equipment - my understanding of what a Halo game feels like has evolved so much since the first game. As a result, Campaign Evolved as a whole feels exactly like Halo now, even if - in the moment-to-moment - it plays like a different game. So going 'back' to the first game where I can sprint, use pretty much any weapon dropped by my enemy (up to and including the Sentinel Lasers of the Forerunner guardians) feels natural. Having recently played Halo: Combat Evolved via the Master Chief Collection, in fact, I felt frustrated by these omissions. The game may be a masterpiece, but it is very much shackled by the architectural constraints of the original Xbox.

Image credit: Halo Studios

My biggest complaint about the pacing of the original game are the last few missions: backtracking through levels you've already cleared, fighting the immensely repetitive and frustrating Flood - it gets tiresome quickly. Especially if you're a glutton for punishment playing on Heroic, Legendary, or - for your sins - Legendary, all skulls on. Campaign Evolved adds enough variation to Flood encounters that it keeps the interest a little higher, although there's only so much you can do to inject life into room after room of zombie-alien onslaught. The wayfinding that's been added to The Library and Assault on the Control Room levels is also a bit patronising; part of the charm in the originals was the expansiveness, the feeling of being dwarfed by a huge planet created by a race of long-dead sentients. Having some little arrows go 'this way, over here!' feels counter to the whole point of Halo, really.

But at least the beating heart of the game is intact: I have long thought of Halo as a 'puzzle FPS', to some degree: on harder difficulties, managing your resources, knowing which weapons to pick up for fodder enemies and which to recover to take down harder foes - sword Elites, Hunter pairs, Wraith tanks - has always been part of the fun. And because of the weird-but-loveable enemy AI, you can respawn into a checkpoint 1,000 times and never have quite the same experience twice. This is all intact in the remake, albeit with more puzzle pieces to use thanks to the expanded armoury and remixed enemy encounters. It softens the experience a bit (and, later in the game, often feels a little unfair in its difficulty escalation!) but it keeps you on your toes. Seeing a platform teeming with Elites, Flood, and panicked Grunts in the closing moments of the Keyes mission, though, felt special. Like this is what Bungie had in mind before it had to start cutting things back to hit the original release date.

Image credit: Halo Studios

But all these iterations come at the cost of something quite nebulous. There was an artistry to the way original designer Jaime Griesemer placed encounters, vehicles, weapons on the map. There was an artisanal feel to the way Halo was crafted; the pace of it remains one of the best FPS experiences to date. Campaign Evolved turns up the dial on fun and approachability, but at the cost of this flow. It's a hard thing to define, but you feel this awkwardness most in the run of missions from The Library to The Maw. Notably, the places Halo Studios has chopped and changed the game the most.

It's not bad, per se, but it's different enough to be jarring. In The Library, for instance, even on Heroic difficulty, you're given a shotgun and encouraged to play the game like an action hero; one-shot killing anything that dares get within spitting distance. You never feel the tension of your ammo running out, rarely feel your armour-plated back pushed against the cold metal wall as 343 Guilty Spark looks on, condescending. It's fun, it gets your heart rate up, but it's not Halo as you remember it. But that's fine, because you can always go and play the Master Chief Collection. Campaign Evolved is trying to give you something different.

Image credit: Halo Studios

The design philosophy is most obvious in the 'Meteorite' package of three new missions that have been added as a prequel to the game, completely original and created by Halo Studios. Taking place a year before The Pillar of Autumn exits slipspace to find the Halo ringworld, the missions follow Master Chief and Sgt. Avery Johnson on a covert operation to infiltrate a Covenant research ship and liberate captured UNSC marines. I rolled my eyes at this when it was announced: 'A prequel trilogy? How droll.' But this trio of missions highlights the differences between Bungie and Halo Studios so well, it almost feels intentional.

Inspired by Troy Denning's Halo books, the writing explores Chief and Johnson's relationship, and introduces a pissed-off Helljumper into the mix to cast a bit of shadow on Chief's heroic status: a bit of in-game colour we're not used to seeing when it comes to Microsoft's de facto mascot. The design of these levels is also curious, if you complete them post-campaign: I think the original Halo is a restrained lesson in FPS design minimalism - you have tools, you have opportunities to use them, you are trusted to do what you will. You're a supersolider, after all. In Meteorite, you are led through a very distinct path, given very specific tools, and are pitted against very specific enemies. At one point, you are literally dumped into a Covenant hunting ground. You must react, not invent. It feels like the Halo Studios philosophy writ large.

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But that's not a bad thing. In fact, after inventing my way through bastard-hard skirmishes in the main campaign, this felt like a treat: a curated blockbuster moment, with high production values, clever ideas, and implementation of all the toys you'd want to see from the wider Halo toolkit. Smart, funny, and self-aware. If this is the future of numbered Halo games, count me in. But it's not Halo: Combat Evolved; a game that felt like a lesson in video game design and player agency. And that, really, is the central point of tension in Campaign Evolved. It's a good game, and I'd recommend it, but it feels wrong to wear the skin of probably the best FPS ever made whilst trying to Michael Bay it a bit at the same time.

I don't think the Unreal Engine does the game any favours in its shakier moments, either. At times, you can see through the flashy facade: it's all a very good homage to the original Halo (which was built in a custom Bungie engine), but sometimes it's just a bit off. The longer you play with the assault rifle, the more you start to see the cracks: bullet spread is a bit weird, time-to-kill varies a surprising amount. Splash damage from plasma grenades and rockets feels unpredictable. Vehicle physics are wonky - even wonkier than they were in the 2001 game. The sound design pales in comparison to the 25-year-old forebear. Again, none of these things are bad. But when you're holding it all up to something iconic, storied, revered…well, the blemishes just show up even more, don't they?

The original Halo is a work of archival significance, a watershed moment for first-person shooters and video games as a whole. Halo Studios had an impossible task in being asked to improve on (or even reinvent) perfection. Campaign Evolved represents a diligent effort - at least at reinvention, if not truly accurate reproduction - and a worthy addition to Halo canon. But it also lives in the long shadow cast by the monolithic status of Combat Evolved. The campaign proper is still one of the best 10-mission runs you can play today, so timeless that Campaign Evolved, warts and all, still establishes itself as a phenomenal entry point for newcomers to the series. And with all the bells and whistles present in this Campaign Evolved experiment, it's a worthwhile skirmish even for Halo veterans. But it struggles to live up to the mechanical and artistic genius of 2001's opus. Campaign Evolved is a game that was always going to be dwarfed by its own legacy.

A copy of Halo: Campaign Evolved was provided for this review by Xbox Game Studios.