Five seconds is enough to execute a perfect plan, sending two enemies to the morgue.

Just as quickly - if not more so - your tactical plans can be left in tatters, as the unit you're protecting is taken out with a single sniper bullet.

Yes, Mode 7's PC strategy shooter has arrived on iOS, and it's as tense, unpredictable, and (mostly) brilliant as ever.

Synchronised shooting

There is a single-player campaign in Frozen Synapse, but the real draw is multiplayer. Two players tap out instructions for their small cabal in green or red, then watch a preview of how the action might pan out. Only then do they commit to their decisions by hitting the 'prime' button.

Once both squadron leaders have taken their turn, the next five seconds of action plays out. You can then see how accurate the preview was (it never is) or how efficient their plans were (often through good fortune as much as fine judgement).

It's a heady brew indeed, almost equal parts order and chaos. There's the precision of your instructions, as you meticulously tap out paths, asking your men to aim in a particular direction, to stand, duck, head for cover, or hug a wall.

Then, there's the noisy, bloody result of your commands, as you sneak up and unload a shotgun into an enemy's back, just as a sniper draws a bead on said killer.

Bad for your stealth

Frozen Synapse is a game of cat and mouse where you find yourself playing both roles. Sneaking carefully can just as easily get you into trouble as rushing headlong into the open. Ultimately, it's about second-guessing your opponent, and maximising any openings he leaves.

The same applies for the campaign mode, where the fearsomely smart enemies don't behave nearly as predictably or robotically as you hope they might.

At times, it seems unfairly hard. Sometimes, the AI here seems a little too savvy - though rather that than the reverse.

'Pad command

Mode 7 has adapted Frozen Synapse sensitively for the iPad, though the game is clearly better suited to a larger, higher-resolution device. And while the interface here is smart, there are a few readability issues.

For example, you'll ask a unit to duck or aim, but the position at which the icon denoting each action appears isn't where you want the change to occur. In a game where a single mistake can be enough to lose, it's galling to misread a situation because of the way it's presented.

And if I really must quibble, the story is a little heavy on sci-fi jargon. The missions themselves are exciting, but the narrative that ties them all together is dry and fairly forgettable.

These are, however, very minor niggles considering everything else that's right about Frozen Synapse. Here is one of those rare strategy games in which immediacy is married with frightening depth. The knife-edge tension of every session means your 50th game is every bit as exciting and unpredictable as your first.