There are a great many twitchy reaction games on the App Store nowadays, with the likes of Pivvot and Super Hexagon leading the way and a slew of less refined but still engaging titles in the chasing pack.

Expander doesn't quite have the simple brilliance to jump straight into the lead, but it does have an engaging quality, and a few tricks up its sleeve. This is a fast-paced and frequently cruel reaction-tester that will keep you entertained, if only for a few hours.

Size matters

The game is all about guiding a rectangle through a linear maze. You control the height and colour of the block by tapping on the right of the screen, and you stretch and squish it by sliding a finger up and down the left.

There are red and blue blocks to collect, but you can only grab them if your cuboid is the right colour. When you're low you're red, when you're floating higher in the air you're blue. The aim is to last as long as you can while collecting as many of the cubes as possible.

The positioning of these cubes is designed to ensure that you take risks. Sure, you could just stay underneath that bridge structure instead of weaving through its struts and other pieces, but then you'll be missing out on all those extra points. Hit the walls three times, though, and you're dead.

It makes for a pretty well-balanced game of risk and reward, and usually you've only got yourself to blame when you try and grab a couple more cubes only for the walls to close in and your run to come to a crushing, early end.

Expanded universe

Unfortunately, there are times when the twitchy, over-sensitive controls let you down and you find yourself crashing through no fault of your own.

It takes a little while to get your head around the concept, too, and that robs Expander of some of the pick-up-and-play appeal of other entrants in the genre.

When Expander gets things right, though, it's a little gem. The occasionally twisting camera makes you readjust, and the tight gameplay will keep your fingers and brain busy for a decent amount of time. It's not a winner, but it's nowhere near the back of the field either.