Knightmare Tower is a powerfully addictive casual game played in short bursts during which you accumulate in-game currency to spend on power-ups. To reach the most expensive power-ups you need to play the game many times over.

You may be surprised by what comes next.

Knightmare Tower, like Ridiculous Fishing before it, is not a freemium game. You cannot pay to expedite your progress, so developer Juicy Beast has worked hard to ensure that you're propelled to the end by good old-fashioned enjoyment.

It's quaint, but boy is it fun.

Eviscerate to accumulate

The similarities with Ridiculous Fishing extend beyond the payment model. Knightmare Tower feels like a brash younger sibling to Vlambeer's game, sharing its furious and thrilling pace of progress and even elements of its tilt-based vertically scrolling gameplay.

You play as a knight who, for some reason, is in a tower that's filling with lava. To escape the lava you have to maintain your upward momentum by tapping the screen to bear down with your sword on the bats, goblins, dragons, witches, wizards, odd potato-like monsters, angry balls of tar, and other assorted baddies that are trying to kill you. For each monster that you destroy you get a speed boost.

Disappearing off the bottom of the screen doesn't kill you, but it brings you closer to the lava, which kills you. Getting hit by a monster or a projectile, however, does kill you.

In each round you accumulate gold coins, and you can spend these on various boosts that help you stave off death.

These include extra hearts, more powerful swords, oil to reduce the amount of friction as you ascend, extra speed extraction power for killing monsters, more luck, and so on. Each of these comes in six exponentially more expensive degrees of potency.

You can also buy potions that let you levitate, become invulnerable, and acquire other magical properties if you come across them while playing.

Towering inferno

On top of that there are achievements and quests, and every so often you somehow rescue a princess, which unlocks another kind of in-game power-up - such as a bomb, a double-heart, or a horn that summons a huge gold-belching potato thing - that appears intermittently from then on.

As with games like Jetpack Joyride, Little Inferno, and - yes, Ridiculous Fishing, the game is only half the game. When you begin, the gameplay is comparatively dull as you weave around the screen trying to poke monsters to death with your puny sword and failing to outrun the lava for any length of time.

But as soon as you unlock your first power-up the fire of addiction starts to burn.

You buy a new sword and suddenly the monsters aren't so much of a problem. You get a little bit further and then you can buy an extra heart, letting you survive for even longer, making more money in the process, until soon you're vaulting up to where the really wild things are, the things that seemed scary when you first met them, and slicing them in half as though they were satsumas.

The game is a pitch-perfect serenade to your reptilian reward centre, creating an inescapable feedback loop in your brain as the promise of better stuff with which to earn more money with which to buy better stuff spurs you on to turn after turn after turn.

It's the sort of paralysingly manipulative gameplay that freemium game designers and fruit machine makers spend all day trying to reproduce.

Only a game

And then it's over. The problem with a game in which the game is only half the game is that when one half is finished the other half is bereft. In Knightmare Tower that moment comes too soon.

After a couple of hours of concerted effort - and it's difficult to play in an unconcerted way - you'll have achieved all the achievements, completed all the quests, rescued all the princesses, bought all the stuff, and rocketed through the tower's ceiling to face the big boss. At £1.99, some might consider that a poor return.

There are technical issues, too. I had to reset my iPad 2 at one point to resolve the jerkiness, which came back anyway as the game sped up, and at certain points the wrong background would flicker on the screen like a subliminal message.

These issues take the shine off a little bit, but make no mistake: Knightmare Tower is an excellent game. If you've completed Ridiculous Fishing, this is the next best thing - a brasher, shorter, glitchier, and less imaginative younger brother to Vlambeer's masterpiece, but in the same family nevertheless.