When an encounter with the beast occurs, it's a chaotic, pulsating, action-packed affairTurtle Rock Studios

I can see them, or rather, I can smell them. Four troublesome humans are taking up defensive positions by a generator which I have been tasked with destroying. They had spent the last 15 minutes on my tail, searching for me as I ate, hid and bided my time. Now as I sit in my final form, the advantage is most definitely with me.

Bigger, stronger and having acquired the ability to breathe fire (always useful) I'm ready to meet my foes head on. Stopping for a long, deep sniff, I take in the surrounding area, smelling the nearby wildlife and the human hunters. After a few more seconds planning my attack, I pounce from among the undergrowth, a massive leap into the heart of their clan.

Minutes later I stand victorious, having killed them all.

Since Turtle Rock Studios announced Evolve, the focus has been on its monsters – called Goliaths – and what it is like to play as one. It is natural to feel drawn to it – after all, everyone wants to win, but in a 4 versus 1 match winning as the one is extra sweet.

The trick for developers Turtle Rock is to make the humans appealing to play as too – and in my short time with the game (I played three matches) they appear to have done a fine job.

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Evolve, much like Turtle Rock's breakthrough hit Left 4 Dead, is about four players fighting together. In this instance however they aren't fighting hordes of zombies, but a single alien monstrosity controlled by a fifth player.

The Goliath gets a 10-second headstart at the start of each the game, but it is a headstart it definitely needs. In its first evolutionary stage the Goliath is weak and the humans have the advantage, so putting as much distance between you and the Hunters is a must.

Each Hunter class – Assault, Support, Trapper and Medic – has its own importance and special abilities. But rather than being bolted-on additions to four effectively identical soldiers, it is the specific abilities of each that you'll be using most.

For example, medics can heal from range, which is crucial as no class heals automatically. Finding a high position above the action is important, as the medic is also able to use two rifles – one which slows the beast with a tranquiliser dart and highlights it for the Hunters to track, and another which exposes its weak points, causing additional damage.

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Assault class is the most standard of the three, and is the one expected to deal out most damage. Support can make his comrades invulnerable for a brief time and call in a devastating barrage attack. The Trapper class is arguably the most important. His primary weapon is able to halt the monster with a harpoon, and he can create a small arena within the map, trapping the monster and making it easier to kill.

As the monster, players start out with two of four attacks and a need to kill and eat as much wildlife as they can. By eating the alien creatures that litter the map, Goliaths fill a meter which when full allows it to evolve. There are three stages, each adding 10ft to the creature and allowing the player to add a third and fourth attack. The third stage instigates the endgame, tasking the monster, on this particular map, with destroying a generator.

As the Goliath, I (much to my surprise) reigned supreme – even making the rep yell out with excitement as I nailed a Hunter with a boulder. It all went surprisingly smoothly, and it being first attempt I was a little apprehensive that it might be too easy for the Goliath.

However, I also played twice as a Hunter, winning once in a tense game that both sides could have lost easily early on. We found the Goliath quickly and he was making no attempt to escape. Making good progress, we found him, but also attracted two of the larger inhabitants of the open map. See, in Evolve the wildlife fights back.

Suddenly we were being attacked by three enormous creatures, including the Goliath. We turned our attention to the two additional attackers and by the time we had dispatched them the final beast was gone.

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The addition of wildlife is an intriguing one. It provides sustenance for the monster but also gives the map a sense of vibrancy and life and can be troublesome for either side. Killing the bigger, more violent beasties also gives Hunters brief boosts to their damage and health, making their disposal more than simple pest control.

The jungle map on show was large and open from the start, with plenty of room for the monster to hide but not so large that nothing happens for long periods of time. Continuing to track the beast after our early lucky escape, we had soon set enough devices (Trappers can set sound sticks down that trigger when the Goliath moves nearby) and the monster disturbed enough flocks of birds (which litter the map) that we had found him.

At this point he was in his second evolutionary stage, and still on the run. As the medic I could see ahead through my rifles scope, and caught a glimpse. Traversing quickly using our Halo-like jetpacks we gave chase and eventually I got a shot on him, highlighting the beast in green and slowing him down.

From there we trapped him and finished the job.

I experienced success on both sides and failure too. Failure was born out of a lack of communication and a medic particularly eager to shoot the Goliath's ankles at point blank range. Contrary to what I thought beforehand, it was as the Goliath that I thought most tactically.

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It is possible, with the right people, for the Hunters to form a cohesive and effective unit, but even without that advantage – and given players who understand their roles – a team of strangers can still fight effectively without much need for communication.

Overall Evolve was fun, and filled with enough to give gameplay a nice sense of variety beyond the initial premise. Being able to play as any Goliath on any map will also mix things up, but there's a sense here that Turtle Rock will need to offer a lot more than the basic 4 versus 1 mode shown off here.

For example, what if there were more than one Goliath and they were also opposed to each other, or what if two teams of humans fought for control of a map while a Goliath roams free, able to destroy the contested areas, posing the question of whether the humans can work together?

Turtle Rock will not be specific what is to come, but do insist there is plenty to announce, including the additional monster designs and multiple fully realised and voiced characters for each Hunter class. Quite what they offer up will be a major influence on the final package, but right now Evolve is a unique, intriguing and fun prospect.