In place of the roller ball, you have the capacitive touchscreen, of course, and this has both an advantage and a disadvantage. On the plus side, you can aim incredibly quickly, just in front of incoming missile tracks and spacecraft, whereas the old roller ball was large and had momentum – it took a lot of practice to use it to aim quickly and precisely, and it took time to move your aim from one point to another.

On the downside, there’s no way to control which of your three missile silos are used to fire missiles – the game’s logic simply chooses the closest. Although this might seem sensible, this system does away with one of the key expert strategies used in the original game – that of using a side silo to lay down a blanket of explosions while you used the centre silo to pick off ’smart’ bombs and anything else that got through. With the current game logic, the centre silo usually gets exhausted first and you’re then into fighting a rearguard action trying to pick off smart bombs low in the sky with just the left and rightmost silos.

On balance, the two factors rather cancel each other out, in terms of game difficulty. There are three skill settings to choose between, but most people, most of the time, will have a challenging and memorable game. The classic Missile Command characteristic learning curve, where early levels are trivial but where the incoming bombardment rapidly starts speeding up, is represented more or less perfectly here, although I did miss the multiple waves-per-level from the original – there has been a definite simplification here.

So far so good though and Missile Command would be easily earning a four star review – but Ultra mode takes it all the way to five, with a glorious reworking of the title, bringing it bang up to date in 2009, with a wealth of digitised backdrops, detailed city sprites and a glorious stereo (music and effects) soundtrack. There’s nothing whatsoever added to the gameplay, but you’ll enjoy this reworking immensely if you’ve got a bit bored of the original’s simple graphics and garish colors.

Cementing the game’s quality is the save game facility, by which (after an interruption) you’re always returned to the exact point you got to in the game. Whether you want to play ‘retro’ or whether you want to pretend Missile Command is a 2009-designed shooter, you’re guaranteed a challenge and this game comes highly recommended.

Dub Siren

With some 55,750 apps in stock, sifting through the inventory to find the gems is getting harder all the time. Then, along comes Dub Siren, which streams music from some of the top Reggae, Dub and DubStep Internet radio stations and allows you to interactively mix music with a wide variety of Reggae effects like horns, beeps, boops and many other sound samples.

Until now, these effects have been exclusive to the professional disc jocks, according to Sawa Digital, the developer. I’m not sure about that, but what I do know is this app is a neat sound effects maker.

Dub Siren has two modes: Dub Mode, modeled after ’70s classic analog synth and Dancehall Mode, which includes popular sound effects used by Reggae DJs today. Switching from one mode to the other is as simple as tilting your iPhone or iPod touch between landscape and portrait modes.

The app has several other features — too numerous to mention — such as faders for volume, pitch, speed and depth. In addition you have the option to select one of three wave effects: sine, square and saw. None of this will make much sense to you if you are not familiar with mixing (I’m not) but it’s big fun to experiment.

You’re not limited to listening to Reggae either. You can play music from your iPod’s music collection in the background by first launching your iPod app and then launching Dub Siren. That’s not a feature unique to Dub Siren. Unlike other apps, though, Dub Siren lets you throw in a spacey simulation of a machine gun over your music if you’re so inclined.

The graphics are exceptionally well rendered and the controls are responsive. I did a lot of experimentation with this app and did not encounter any glitches or bugs.

Sawa Digital says pro DJs can use the Dub Siren and a iPhone or iPod touch as a standalone Reggae sound effects machine because it features a sophisticated audio algorithm and uncompressed audio files. I’m not entirely sure what all Dub Siren is capable of doing —I don’t have a musical ear — but it sure sounds good to me.

• app_name: Dub Siren
• rating: 9/10
• price: $3.99