As everyone knows, the main danger when setting off your own fireworks display is the likelihood of losing an arm in the process.

Those Government-sponsored adverts may talk about kids scolding their hands if they forget to wear their gloves while holding a sparkler, but the true worry is the risk of ending the night with missing limbs.

That's not because of any rogue explosions, of course, but the possibility of neighbours disturbed in their sleep coming at you with pitchforks.

A much safer way of conducting your own display is delivered in Alien Decursion. No doubt not the developer's intention, the process of eradicating wave after wave of alien attacks - the touch of your finger causing them to pop into several million pieces – results in a more than adequate fireworks fiesta.

Learning your lines

That's largely because, rather than chucking in aliens at random, Alien Decursion is a highly scripted affair.

Your job is to protect a grounded weapon from their attacks by, in the main, tapping the aliens as they come into view. Initially one tap is enough to cause them to burst, but as their species diversify, so how you deal with them also has to evolve.

Some can only be destroyed by holding your finger down on them for long periods, for instance, while others are splattered by several mini taps - the equivalent of working a jackhammer with the tip of your finger.

There are also bonuses on offer that keep your home area safe; a drag down to your base enough to keep you ticking over.

When all such inputs are combined, what starts out as a simple reaction time test soon turns into something rather more hectic.

Within just a few levels, your fingers start having to dart all over the screen at the same time, switching between set taps and longer prescribed moves all just to survive and do it all again a few seconds later.

Strictly thumb dancing

It's the predetermined nature of the attacks that, somewhat amusingly, turns Alien Decursion into something of a finger dance. It's almost like playing an instrument, with every twisted and unnatural position your hand takes up defined by the blood-thirsty blobs that appear on screen.

It's no exaggeration to say that, when the pace gets going, Alien Decursion has much in common with Konami's Dancing Stage series – assuming you like to mount its arcade cabinets with your fingers, that is.

However, while you might think simply playing by Alien Decursion's rules would be enough to get you through, this is a game where the rules keep changing. As stated, each new alien has to be dealt with differently, but learning what you need to do only comes with experimentation.

There's no guides or hints given beyond the opening tutorial, meaning levels can be fluffed two or three times simply because you're not sure just what's required.

Decursion day

Aside from this, there's a distinct feeling that, once you've conquered a few levels, there's not much else on offer. Alien Decursion gets harder and harder with every round, but it's arguably missing that special something which would transform it from a good game into a genuinely great one.

That's actually a request rather than a criticism, because there's much promise to build on here.

Alien Decursion's simple, purposely unsophisticated design style certainly deserves a little more exposure, and if developer Tom Bradley can add an extra spark or two to the set up, Alien Decursion's second invasion would be even more welcome than its first.