The tower defense genre has been steadily growing for a few years now,  with many such games spicing up the recipe with unique elements to stand  out. Enter Sanctum, the latest game to carve out a niche on an  increasingly crowded landscape. In this downloadable game, you build  towers to protect a key structure from gangs of marching meanies, as you  do in most such games. But here is the hook: While those monsters  maraud down their predetermined paths, you take aim at them with your  own weapons from a first-person perspective. Having to face those  lumbering monstrosities makes Sanctum a more immediate experience than  your average tower defense game; you can no longer be content to watch  from above and must meet the terrors head-on. It's a shame there aren't  more ways to enjoy Sanctum: It only comes with three different levels,  but with 20 or more waves in each, they are lengthy ones. Though you may  wish that the concept had more content built around it, what's here is  fresh enough to make Sanctum a fun way to while away the hours--even if  you're burnt out on the genre. 
Slow these suckers down by making your maze as twisty as possible.
In many respects, Sanctum is like most other tower defense games.  Monsters emerge from predetermined spawn points and meander (or float,  or scamper) down predetermined paths. Your goal is to destroy them by  placing turrets along that path at strategic points. You also need to  extend these bumbling buffoons' journey as best you can by building your  turret blocks in such a way as to create mazes for them to traverse.  While you're probably used to placing towers from an overhead view, in  Sanctum, you do so from a first-person view. This can be disorienting at  first, especially when planning out your maze. Luckily, you can switch  to an overhead view to see how your labyrinth is coming along, though  you can't actually build anything this way.  
Maze management is only half of the equation, however. Once you've spent  all your allotted resources, you press a key, and the invasion begins.  Obese creatures on spindly legs, giant lanky bobble heads, and other  oddities descend upon your maze. In other tower defense games, you hope  and pray that your turret configuration is clever enough to destroy  them; in Sanctum, hope and prayer are no substitute for a warm gun in  your hands. As such, you use one of three weapons--an assault rifle, a  sniper rifle, and a gun that slows enemies down--to give your turrets a  helping hand. The shooting on its own isn't particularly satisfying.  Monsters are oblivious to your presence, and in spite of the blood and  goo that erupt upon a deadly headshot, there's little sense of impact.  But when the mutant parade is in full swing, you'll be too busy sniping  floating spores to give it much thought.  
                                                  Enemies  won't kill you if they ram into you, but they do knock you around. It's  best to stand on your tower blocks and shoot from above.
 You make the most important strategic choices between waves. Do you  spend resources on upgrading existing turrets or build new ones? Do you  upgrade weapons or flesh out your labyrinth even further? You must be  conscious of what enemies will be next coming down the pike when  considering these questions. Bobble heads are most vulnerable to your  own weapons, so an upgraded sniper rifle may be the way to go. But  attending to the bobble heads might mean leaving the walkers that  accompany them to your turrets, so you have to find an appropriate  balance when spending your dough. The single-player portion of the game  features a nice difficulty curve, allowing you to get your bearings  early on and putting what you've learned to the test by the time you  reach the final level. When you leave the campaign behind, you can join  friends or strangers to tackle endless waves together. Developing a  strategy while working with two resource pools is great fun, though the  challenge ramps up considerably faster here than in single-player, so  much so that you might get frustrated by how little damage even your  fully upgraded weapons are doing. Unfortunately, there there are no  other modes to conquer.
That wouldn't be so bad if Sanctum came with more than the three  included levels, each of which is divided into 20, 25, or 30 waves.  There is the expected replay value here in the form of multiple  difficulty levels, and the strategic flexibility means you might have  fun replaying levels to try out new approaches. Nevertheless, three  levels is a low number compared to other such games, and at $14.99, you  would rightfully expect more variety. (Consider, for example, such  content-rich games as Toy Soldiers and Comet Crash,  both of which delivered their own innovations.) At least these levels  are lovely. Sanctum was created with the Unreal 3 engine--a fact you  would probably notice early on, based on the telltale texture fade-in on  your weapons and elsewhere. Yet the environments are undeniably  attractive. Monsters emerge from thickets of lush flora where you  glimpse birds flying through the sky. Giant glimmering flowers tower  above, next to bulbous green orbs in which luminescent liquids  flow--nature's answer to the lava lamp. It's a typical "sci-fi jungle"  look, but it is evocative enough to hint at the possibility of a world  beyond your limited game grid. Evocative, too, is the ambient menu  music, which is unmatched by the more typical electronic beats you hear  during gameplay.  
                                                  It's like March of the Penguins, only instead of penguins, they're freaky tentacle monsters with glowing eyes. And they float.
 Sanctum may not be bursting with features, but it's different enough to  draw your attention, and it's entertaining enough to keep it. Online  leaderboards and Steam achievements provide further incentive for you to  keep playing, though they aren't substitutes for the variety that more  levels and modes would have offered. But what's here is nice to look at,  enjoyable, and often challenging. And when you take in the mess of limp  corpses clogging your passageways, or snipe that last soaring menace  just before it reaches its destination, you appreciate what Sanctum  brings to the genre.