Gorgeous graphics, FPS controls and a persistent MMO world with dropships and jetpacks. Firefall's specs may have you already reaching for your wallet, heading to the website and looking for the preorder button. Whoa there. Save that disposable income for the double-dip recession: Firefall will be free.

It's a team-based shooter, a mash-up of FPS and MMO that wowed us when we first glimpsed it : mercenaries strapped into jetpacks, hopping in teams across a beautiful, cartoonishly bright landscape. It's all the better for knowing that you can be simply called to action by the server, bundle into a giant ship and head off to another part of the world – where a boss might be stomping all over a human village.

You fight to protect humanity from the evil Chosen, as part of a small squad of five. You roll around the world looking for action, other players, or Crystite. Crystite?

Here to answer the obvious question, Firefall's executive producer James Macauley: “Crystite is basically our primary source of energy in the world today, and so it has become the biggest currency. People trade in Crystite – they buy upgrades for their Battleframe and Backpack [the bulky suit and power supply] or their weapons in Crystite, and it's also what's used to upgrade most of the tech the armies retrieve.”

Crystite: it's both a currency and a resource. There's an economy and therefore a reason to fight.

Your class will depend on your own Battleframe's configuration, as Macauley explains: “A character will have access to all the Battleframes, but you level up each Battleframe independently – and this was a pretty important design decision for us – in order to give you quick access to the different classes depending on the situation that you're in.

“You'll be able to swap out your backpack, pick different weapons and customise what abilities you install in your backpack. You can actually install custom modules into your weapon to change how it fires, change the reload time, the accuracy, or even its alt-fire mode.”

So there's a depth to the character creation and combat that you'd expect from a modern shooter. But for it to work, the MMO side of things needs to be just as well defined. How will they mix the action into the world? Macauley: “We thought it would be really cool to have things happen based on time of day, time of week or even seasonally. So you'll log on in the middle of the night and you may see creatures that you won't normally see during the day, but you may have NPCs that are going about doing some covert operation that you haven't seen before. We want the world to change based on what players are doing and so it's unpredictable. Based on what players have been participating in, the events players have chosen to do or what missions they're running and the time of day, various things may be happening.

“You may actually see a Chosen attack on an outpost or you may see a corps of humans fighting back and pushing those Chosen back into the building. We're really trying to create this dynamic world with lots of things happening and that's driven by a variety of different factors, including what players are doing.”

At a higher level, beyond the squad, all this can benefit your clan. Squads are temporary, but the clan is where you'll see real gains. You'll have access to shared resources and some stats will be tied to your army's growth. Most excitingly, there's a shared tech tree to advance up, as Macauley describes: “One thing that we're really excited about is having shared common goals within your army. We'll actually have an army tech tree that you can choose to advance as a team. You're making strategic decisions on where you spend your resources and where you spend your time trying to advance your technology, so that each army actually may be completely different. You may specialise in one area of the tech tree, whereas my army may specialise in a completely different area.”

You'll pay for all this, but through microtransactions. With a combat-based game there's a temptation to allow players to simply buy up skills, but Firefall is deliberately avoiding that game unbalancing route. “We're not going to sell a weapon that does more damage... that just does a mega amount of damage where you're going to get an instant headshot or instant kills,” Macauley states.

Instead you'll probably be paying for aesthetic changes to your avatar, or gender and name changes. For people unable to spend as much time playing that they'd like, they're considering allowing them to purchase multipliers to improve their Crystite collection.

Firefall is starting to sound startlingly ambitious, particularly when you consider it's a free game.