If they are to attract a packed audience, tower defence games must perform the kind of delicate balancing act normally reserved for tightrope walkers.
On one hand, you need to introduce a constant sense of peril where safety is never guaranteed. On the other, you need to allow players to feel relaxed enough to enjoy the show before those heart-in-mouth moments hit.
GRave Defense HD deserves a polite round of applause when it comes to that first skill, yet its punishing difficulty means all but the most hardcore of tower defenders will be too burned out to ever see the grand finale.
The walking, and flying, deadArtOfBytes’s game works best on a visual level. It offers the same generous, 20-level campaign as its low-res progenitor Grave Defense Gold, but with lush backgrounds that really shine on large screen phones and tablets.
From humble graveyards to tropical rainforests and a bizarre trip to the Bermuda Triangle, each map is intricately detailed with subtle effects like flowers waving in the breeze to dazzle players.
The globe-trotting campaign is linked to an entertaining but deeply derivative plotline that fleshes out the stock tower defence gameplay.
Basically, you're the last hope for humanity in a post-apocalyptic world, where zombies have risen from their graves to hunt out the last human survivors.
As the story progresses, via orders barked out by a military cliché between maps, some 19th century horrors rear their monstrous heads in some brutally tough boss battles.
We’ll avoid spoilers, but suffice to say one of them has a fondness for cloaks, castles, and arterial fluid.
Towering criticismWhile the first level does an efficiently friendly job of guiding tower defence newbies into the fine art of tower defending, from the second mission onwards the game proves to be a cruel, remorseless beast.
This writer started off on ‘Normal’ difficulty, but was clobbered brutally enough on the next few levels to switch to ‘Casual’ until the mechanics became more familiar.
The touchscreen-friendly system of tapping on available spots to place auto-firing weapons, divided neatly into ones that will attack ‘air’ or ‘ground’ enemies, is spot on, while upgrading and removing items is a breeze thanks to context-sensitive tap menus.
The issue is the sheer volume and toughness of your foes.
Enemies advance down fixed paths, which are initially shown with a helpful line of red dots, but have a range of entry points - meaning you have to spread resources pretty thinly to ensure a new wave doesn’t slip through your net of death.
It’s too common to survive a dozen waves by the skin of your teeth only for a new enemy type to suddenly appear and stroll through your defences, end the mission in defeat, and undo more than ten minutes of work.
Plus, somewhat bafflingly, the whole map doesn’t fit on one screen, and occasionally you need to scroll by swiping the edges to see where enemies are spilling from.
Don’t get me wrong - for serious fans of the genre who relish a mighty challenge GRave Defense HD is a title worthy of your strategic prowess.
More casual players, though, might want to wait for Plants vs Zombies to shuffle onto the Android Market.