Charles followed his gaze.  The aliens had decorated their passageways with artworks, but there was no recognisable pattern at all.  It looked as though a child had taken a paint box and splashed its contents randomly over the bulkheads.  Charles suspected his five-year-old nephew could have done a better job, then he touched the bulkhead and realised that the texture changed from colour to colour.  Could the aliens be colour-blind?  It might explain their choice of artwork ... and, for that matter, the apparent shifts in their own skin colours.

Or maybe they just have a different set of aesthetics, he told himself.  If humans can’t agree on what makes a good painting and what doesn't, why should they?

The explosion caught them by surprise, despite the drones.  An entire bulkhead blasted out at them, forcing the Marines to duck and dive for cover, despite their armour.  Behind it, a squad of aliens lunged forward, firing plasma bolts towards the human intruders.  The Marines returned fire, blasting the aliens to the ground.  Their tactics made no sense, Charles noted absently, part of his mind analysing the brief engagement.  Or perhaps they did make sense, he realised, as the second group of aliens appeared.  This group seemed far more professional, sniping at the humans from cover rather than merely charging at the intruders and being gunned down.

There was no time to pick out an alternate path through the rabbit warren.  Instead, Charles barked orders, commanding his men to launch grenades into the alien position.  The deck shook violently as the grenades detonated, followed rapidly by a sudden reduction in enemy fire.  A small group of Marines ran forward, crouching low, and finished off the remaining aliens before they could escape or recover from the blasts.  But a second set of aliens had taken up position behind the first ...

Charles sighed, resigning himself to heavy fighting.  The HUD kept updating rapidly, showing more and more concentrations of alien crewmen.  It was impossible to tell which of them were trained soldiers – alien Marines, he guessed – and which ones were merely crewmen who barely knew which end of a weapon to point at the enemy.  The Royal Navy was often careless about ensuring that its starship crewmen kept up with their personal weapons; he couldn't help feeling a flicker of amusement at the thought of the aliens hadn't the same problem.  Making a mental note to suggest to the Captain that weapons practice should be made mandatory – the aliens might be the next ones to board a crippled starship – he barked orders, leading his Marines further and further into the alien ship.