Az: Sky Defender 3D

It's never a great sign when the only review for a sci-fi shooter on the Android Market is posted by an obscure app site which praises it for being "very practical and interesting."

Az: Sky Defender 3D may be many things - such as a bizarrely named, ultra-generic, ‘bullet-hell’ blaster with brutal difficulty spikes - but it is neither particularly “interesting” or “practical”.

Seriously, how many giant flying stingrays do you fend off with laser bullets every day?

With no attempt at a backstory or even a tutorial, Az: Sky Defenders 3D hurls you into vertical-scrolling air combat with an invading alien race that has a distinctly fishy feel about its design.

Initial impressions are disappointing: the sparse, repetitive countryside backgrounds against which combat takes place, an interminable looping synth soundtrack, and low-rent explosions reminiscent of a village fireworks display.

The touchscreen controls prove a little better, with the default scheme - in which you navigate your vulnerable little vessel by sliding it around the screen with your digit of your choice – pretty responsive for aiming.

Admittedly, dodging tiny bullets is tricky with chubby fingers blocking off about a third of the screen, but compared to using the clunky alternative D-pad method, it’s a dream.

It helps that the early enemies, which look like disembodied squid heads, are easy enough to dispatch with your tiny ship’s auto-firing laser cannon.

Pretty quickly, however, you’re squaring up to some giant, armour-shelled space rays that rattle off shoals of stinging laser bullets for you to weave between as you desperately aim for their prone googly eyes.

Survival soon relies less on skill (the most essential component of any rewarding shooter) and more on your patience for grinding through one of the already completed 40 missions to collect cash from downed enemies.

This can be spent on acquiring upgrades to your arsenal, from extra cannons to tougher armour (all with different power levels to unlock), which give you a slight edge in battle.

With scaly enemies and reasonable controls the only real draws here, Az: Sky Defenders 3D will hook you in for a bit, but it then deserves to be chucked straight back.