Sharing its fiction with the SyFy-produced television series of the same name, Defiance is a cross-platform MMO third-person shooter set in the blasted remains of San Francisco Bay. Last weekend saw the final Beta event before its release on Steam on April 2nd, and I was able to jump in for a good 20 hours or so. It doesn't come across well in screenshots and there are certainly lessons the developers could learn from beta, but I certainly enjoyed tooling round the post-apocalyptic landscape in my buggy, gunning down oversized alien insects.

You take on the role of an 'Ark-hunter' scouring the Bay for extraterrestrial technology following an apocalyptic war with invading alien species. You can choose to be either a human or an Irathient (a humanoid alien species seemingly modelled on the cardboard cut-out monsters of 1960's Doctor Who) before deciding which upgrade path to go down. Defiance doesn't nail the player to a class, instead letting you select an 'origin' - a starting weapon and outfit - before ushering you into the wasteland. Not that the choice of threads is a particularly appealing one: the default costumes leave the players looking like they've been in a devastating squabble with a corduroy supplier.

All Ark-hunters have been implanted with an EGO - a form of AI that helps you navigate the environment and provides a hub for upgrading and equipping perks. After the tutorial you choose which skill to invest in. 'Overcharge' provides a higher damage output and reduces recoil, 'Blur' boosts movement speed and melee attacks, 'Decoy' spawns a copy of yourself to distract enemies and 'Cloak' makes you invisible to enemies and recharges your shields. EGO points, gained through quest completion, then unlock further perks or upgrade your existing ones. The interface is a bit of a jumble, but it does allow you to unlock perks from different upgrade trees, allowing a degree of hybridity.

As in developer Trion's monster-slaying MMO Rift, huge dynamic global events dominate the landscape at random intervals requiring a huge concerted effort to resolve. These are known as 'Arkfalls', showers of debris from alien spaceships which crash down to release waves of enemies. You have only a finite amount of time to eliminate them before snatching the loot within.

There's no observable difficulty scaling, however, which means you really do just need a huge crew to take on these events. Groups of two or three players can succeed through attrition, but the battles might last up to half an hour - a gruelling tussle which sees your entire team being wiped out time and again. Meanwhile, put together a squad of 10 to 15 and you can barrel through the challenge in a matter of moments. There's something to be said for incentivising big-team play, but the devs may not have found quite the right balance.

The shooting itself feels similar to Borderlands - for good and ill. As in that game, there are more than enough guns to pick from. Defiance boasts several hundred radical variations based on a core set of 15 weapon archetypes, but, also as in Borderlands, most of the early-obtainable combinations feel low impact. Nonetheless, this provides a potent incentive to participate in Arkfalls and sidequests as mod packs are available as loot.

Only 2 regions were open in the Beta weekend with several more accessible in the final release. It's an expansive world to be in, and its occasional vistas are really where it looks its best, so it'd be a shame to have to fast travel everywhere. Luckily, you can spawn a vehicle in front of you instantly, allowing a scenic tour to enjoy the exotic plants and mountain sunsets as you drive to your destination. The driving physics are very floaty and arcade-like but that does not diminish the pleasure in boosting up almost vertical terrain whilst splatting mutants off your fender.

Defiance follows Guild Wars 2's payment model: it's a one-off purchase requiring no subscription fee. Microtransactions are available but are almost entirely cosmetic items and XP boosts. Perhaps a bigger question is how the game will tie into the ongoing TV series. We've been told that one will heavily influence the other, but juggling two wildly different and equally risky projects makes the fate of both less certain. That said, it's a bold experiment in cross-media entertainment, and if the TV series' need for evolving drama means the game is maintained with new and diverse content, Defiance could be one of the surprises of 2013.