There's no escaping the fact that geoDefense's debut on Windows Phone is one full of contradictions.

Given the game's take on tower defence is three years old, its stripped back setup undoubtedly bears the hallmarks of a 'classic' rather than something fresh.

Yet, by the same turn, its futuristic setting feels far more contemporary than the times-of-yore approach adopted by scores of its competitors.

But, the most striking contradiction is the one that managed to divide those who took on geoDefense on iPhone: despite being stupidly simple to pick up, geoDefense can be devilishly hard.

Simple start

For better or worse, that's a factor Critical Thought has made no attempt to alter here.

Just as was the case back then, levels appear simple enough on first glance – enemies glide down one path towards the gate at the end of the stage – but mounting a defence to keep your foe at bay takes considerable practice.

Presuming you have enough credit (earned by downing your enemies as they sweep past), towers can be dropped into play alongside the route to goal by tapping and dragging them into place.

Once they're set, they begin firing automatically as geoDefense's invasion force begins to fly by. Some pass at a steady pace, susceptible to your shots and wiping out after just a few seconds. Others require several attacks before they're downed, and the speed at which they zip past means your opportunity to target them is severely limited.

Trouble at the top

Inevitably, some will always slip by. Survival in geoDefense doesn't rely on your ability to keep an entirely clean bill of health. Instead, restricting your enemy's attacks to ten or more will see you through.

Even this, however, is no walkover. Just as your foe varies in shape and size, so your towers sport various abilities.

Aside from the standard shooter, some towers fire lasers in straight lines, while others release missiles. You can even equip a tower that slows the enemy nodes down, leaving them wide open to further attack.

But fitting the level out with each and every tower on offer won't win the day. Rather, both the type of course and the enemies that inhabit it determine your best line of defence. For example, laser towers make little to no impact on bendy tracks, while other stages are won by upgrading your defences to the max as soon as possible.

Such is the topsy-turvy nature of geoDefense that trying to pull off the latter in each of the levels on offer (separated into easy, medium, and hard) will see you beaten as frequently as you triumph.

Old at heart

It's this very trait that splits geoDefense's audience. For some, it's evidence of an old skool, almost 'pure' approach, where you're constantly challenged to change your strategy and think on your feet.

For others, geoDefense falls far too quickly into trial and error territory, bowing to a difficulty curve that remains far too steep.

In truth, geoDefense on Windows Phone sits somewhere between the two. There's no denying that the need to repeat a growing number of stages has the potential to frustrate, but the no-nonsense approach to play means a restart is never the ordeal it might first appear.

It's this ability to keep you glued even if victories are scarce that finally puts the game's supposed contradictions to bed: flashy futuristic setting or not, geoDefense is every part the old skool puzzler, and that's the kind of hardened challenge that never gets old.