If you haven't played it, you'd be forgiven for not understanding why Mirror's Edge, a game that fell short critically and commercially when released back in 2008, is still considered important.

The elevator pitch for its sequel, announced six years later, is hardly as self-explanatory as, say, Red Dead Redemption 2 or Half-Life 3 would be. And yet, while this would have been considered ludicrous just a few years ago, Mirror's Edge Catalyst has emerged at Gamescom 2015 as one of the most promising games of the show.

All it takes are a few seconds of play to remember exactly why its predecessor carried so much potential. Vaulting across the rooftops of the sharp and ultramodern fictional city of Glass is as quietly empowering and exhilarating as ever. As you clamber up drainpipes, hurdle railings, slide into ventilation shafts and make death-defying leaps across the skyline--often in one beautiful flowing motion--it feels as though you are pushing the human body to the peak of its physical possibilities. No studio other than DICE has managed to capture this solitary Zen of first-person urban parkour so wonderfully.

Crucially, its heroine Faith remains as easy to control as Mario. Two buttons and two analogue sticks are usually all you need to dash and spring across the city. The Xbox One Controller's Left Bumper (PS4: L1) is the 'up' button, which ordinarily results in a jump, but is also used to climb upwards in certain contexts. Meanwhile, the Left Trigger (L2) is 'down', which can mean crouch, or slide, or dropping from ledges, etcetera. In a game that hinges so much on how it flows, simplicity is king.

As a concept, fluid and foolproof first-person platforming has always seemed like a bridge too far. But the thought that DICE has put into Catalyst means that players will have a comprehensive understanding of the basics in a matter of minutes. Your doctorate in parkour begins from that moment onwards.

This is perhaps best demonstrated in the time-trial segment of the Gamescom demo, which is the first challenge that most players encounter. The goal: Jump across various rooftop real estate and reach the end point in the fastest time possible. On my first attempt I crossed the line in about 45 seconds, and yet when returning to the challenge some 10 minutes later, all the advanced free-running tricks and ideas I had learned meant I was able to shave off an additional 15 seconds.

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It's the purity I love. I didn't acquire speed boosts or jump perks; I unlocked my own ideas. So, instead of thinking about how I could clamber across a mesh of ventilation tunnels and pipeworks as fast as possible, I began to realise I could instead leap across the whole obstacle entirely if I wall-dashed across a building that overlooked it.

Combat, meanwhile, is built to take advantage of the momentum you build. Press X (Square) in the middle of a dash, or at the crest of a jump, and Faith will launch herself towards a nearby enemy. Approach speed is key here; pressing X whilst running at full-pelt will result in a haymaker roundhouse kick, and doing the same mid-jump will trigger a pounce maneuver where Faith uses an unwitting enemy as her landing cushion. Attacks, like every other main command, are context-sensitive, so even when sliding across the floor, pressing X will make Faith hurtle towards an enemy's knee-caps.

Conversely, a lack of momentum is punished. When standing toe-to-toe against Catalyst's armed soldiers, fights become more evenly balanced, at the cost of your health. Unless you approach at speed, the grunts will get their jabs in.

The Gamescom build was described as "pre-alpha", but Catalyst's gameplay fundamentals already show a wonderful elegance and fluidity. Yet fans of the series would be quite right to point out that, actually, everything positive written so far could actually be said of its predecessor.

So what, exactly, is new in Catalyst? That's a harder question to answer, and there are a couple of great ideas. The first; Catalyst's map is open world, meaning that a choice of missions and side-quests will be presented to the player at any given time. Placing a waypoint on the map results in a red breadcrumb trail dotted across the game world. Imagine a parkour satnav system and you're close (but don't worry, the red trail tends to be artfully and unobtrusively placed along the geometry--it's not as though a giant red paint-roller has been let loose across the city.)

The second notable addition are the new puzzle elements found within the beautiful neo-IKEA building interiors. With level design seemingly inspired by Portal 2, some rooms present exit points that are simply too far out of reach for Faith. Players need to scan their surroundings and mentally build an idea of the best way out.

Aside from these two welcome additions, the developer hasn't revealed much of anything new that wasn't in the original formula. But to an extent, this is fine. The first Mirror's Edge was just a few leaps short of becoming a masterpiece precisely because of the poor thinking that was stirred in. For all its blissful first-person free-running and thrilling getaways, there was a maddening checkpoint placement, a weak story throughout, and eventually a rather spineless resort to handing the player a machine gun. Will Catalyst make the same missteps? No signs of them yet.