Sanctum was a generally well-received tower defence/first-person shooter hybrid, the brevity of which was its main downfall. With Sanctum 2, it appears that Coffee Stain Studios has not only addressed that complaint, but has also faithfully adhered to the rules of the sequel: it’s bigger, better, and there is more to do.

Mechanically, things are as expected in a tower defence title: building and extermination phases alternate, sometimes with a timer, sometimes without. The player (or up to four players in online co-op mode) defend the core of their base against hordes of incoming aliens by collecting resources before purchasing and placing barriers and weaponised towers on the battlefield. During the building phase, items just placed may be refunded at no loss, and amusingly, towers may be dropped on others or oneself, inflicting damage.

Sanctum 2 preview

A handy arrow shows the route incoming hordes will take, and as things escalate the intruders emerge from multiple points on the map. Some are able to fly, pass directly over barriers or smash directly though them. Barriers are low enough that players may hop atop them with a single jump for a better view of the action. However, getting that close to the creeps puts the player in harm’s way, and unlike its predecessor, Sanctum 2 features death and a respawn mechanic. The regenerating health system prior to outright expiry is similar to that found in most modern FPS titles – if somewhat slower – and low health not only drains colour from the screen but also drastically reduces running speed.

Sanctum 2 preview

The game’s four classes are familiar, with a sniper rifle, rocket launcher, shotgun, or assault rifle featured as locked-in primary weapons. There is also a second weapon slot, and for starters, one perk slot. The good news is that weapon and perk unlocks carry across all classes, and that all weapons have a secondary fire that might be a charge up or weaker homing shot, for example.

While smart barrier placement is essential, the emphasis in Sanctum 2 is on shooting rather than letting the turrets do the work. Combat involves a lot of juggling between weapons, as provided it is empty, a holstered firearm will reload automatically. The insectoid enemies all feature glowing weak spots where they take much more damage, and attack a range of ways, from melee strikes that propel the player backwards, to missiles from the air, to area of effect attacks that are dodged with a well-timed jump.

Sanctum 2 preview

There are 16 maps in Sanctum 2 as opposed to three in the first game, and these are split over four types of terrain, from gleaming space bases to greener parks. Each contains between 6 and 10 waves, and the damage the base’s core takes carries over for a whole map, making latter waves with tougher enemies particularly challenging. If the core is destroyed, the players are sent back to the first wave and must start building from scratch. Co-op play scales enemy damage up and resources are shared rather than duplicated, but it feels like the easier way to play.

At this stage, there seems little to complain about in Sanctum 2, particularly once its US$14.99 price is taken into account. There isn't much story beyond “AHHH!!! ALIENS!!!”, but that’s a function of the genre, and online play is impressively seamless. Perhaps the only grumbles are that the guns feel a bit weak, and there is a slight lack of character – it all seems a bit clinical and antiseptic. Despite that, Sanctum 2 is shaping up to be the best tower defence/FPS mashup on the market.

Sanctum 2 is out on Xbox 360 and Windows PC on May 15, and on PlayStation 3 shortly thereafter.