The problem with success is that it leads to saturation, and at the risk of sounding like a certain Vodafone-shilling muppet, that leads to suffering. As soon as you know Kingdom Rush HD is a tower defense game the brain starts ticking over with comparisons: the best and worst and the many, many more that operate in a limbo of mediocrity. But what's important about Kingdom Rush HD isn't really the genre. It's the fact it's absolutely awesome, and has a structure that makes it even better.
At a base level, Kingdom Rush HD is gorgeous and works in a standard manner. But think of that as the scaffolding for each stage. The game's core is a set of upgrade systems that take the nondescript soldiers, archers, mages and artillery dwarves you start off with into the stratosphere. Each unit has three 'basic' stages where, for example, the archers become better shots and able to shoot faster and farther with each step up. Then after that, the path forks in two.
Snipers, capable of shooting insane distances, headshotting any enemy instantly, and laying down AoE bursts of shrapnel on nearby enemies? Or forest rangers, who turn them into pincushions filled with poison arrows and trap entire groups with grasping thorns? Templars or barbarians? Do you want a Tesla Cannon that fries enemies with lightning that jumps between individuals, all the while dealing constant AoE shocks to anyone that even enters its vicinity?!? Of course you bloody do. And Big Bertha... oh man. I'm getting hot just thinking about it.
This is a game that not only has a brilliant twist to the fundamentals, but seals the deal with a level of polish far beyond what is usual, or even unusual. We'll come to the mages in a second, and I can't wait. It thrills me just thinking about playing it again, because I know that every time I do I'm going to hear the map music, and about ten seconds in get a big burst of adrenalin when it boots into epic mode.
Every aspect of Kingdom Rush adds a little something different, from the farmers you can place manually every ten seconds to split waves, to the constant chatter of your troops, to the way in which enemies buff one another or certain bosses disable towers and have you frantically tapping as they saunter past a frozen Sorcerer.
Ah, the Sorcerer. And the Arcane Wizard. Of all the units in the game the mages do something funny to my stomach, because their abilities when fully upgraded are just... well, magic. Sorcerers shoot energy bolts that wrap around their targets, dealing huge damage and de-buffing them. You can also simultaneously transmogrify enemies into sheep, and summon giant earth elementals that pound things into dirt. Arcane Wizards shout French-sounding things as they zap foes into dust, lancing others with arcing purple lightning, and teleporting giant groups back up the path like it ain't no thang.
Perhaps I get too excited by all this stuff, but that's the measure of Kingdom Rush. Every enemy killed yields gold, and as the figure ticks up to the point where you can afford a mega-unit the game always seems to sense it, upping the intensity to just that level where you need a bad mother cruncher STAT to hold the line.
I haven't even mentioned the upgrade system, where you can use the stars earned on each level to buff your units permanently, and reset and redo it as many times as you like. Or how each level, once complete, offers Heroic and Iron Challenges with limited resources and cleverly-balanced enemy groupings. These reward you with another precious star and a prettier completion symbol. This is the kind of game where you actually care what the world map shows about your progression, and there aren't many of those.
Kingdom Rush HD is a tower defence game and, while it would only expose my ignorance to say it's the best ever, it's certainly my favourite. I swoon for its little soldiers, clench my teeth when a position is overwhelmed and a flood of fangs bursts through, before punching the air in delight when my forces somehow, by hook and crook and magic book, hold out in what seems like an impossible situation. It's an absolute belter and, on iPad at least, you simply can't do better.
App of the Day highlights interesting games we're playing on the Android, iPad, iPhone and Windows Phone 7 mobile platforms, including post-release updates. If you want to see a particular app featured, drop us a line or suggest it in the comments.