I ran the example adventure in the back of the rulebook for a group of three players.
The Players
Brother Ivar, Space Wolf Tactical Marine (Player: very familiar with the 40K background and d100 system).
Brother Astramael, Blood Angel Assault Marine (Player: growing in understanding of the 40K background and d100 system).
Brother Invictus, Ultramarine Apothecary (Player: still unfamiliar with 40K background and this was only his second taste of the d100 system).
Setting Up
Ivar and Astramael made their characters at the same time (sharing the same pencil - go team bonding!) while Invictus added later. I included in the character creation process my own "Deathwatch Origins Chart" which I will post on the forums because I do really feel it benefits a starting character.
I had a read of the adventure - fairly simple stuff. Most confusing aspects were:
1) How many players it was made for?
2) How difficult is it supposed to be?
3) Keeping track of the time in an interesting and dynamic way.
I found some music on youtube, (enter: "Warhammer 40,000 Apocalypse" and also "Warhammer 40,000 Protectors of the Imperium of Man") which I cannot recommend strongly enough. The 40K world is enhanced so much by this style of music.
Personally I played it at the start of the session as I read the fluff introduction (which was just when my partner returned from work at the climax of the speech - to quote "I've never been so attracted to you....." ) and during the final conflict of the mission to really go out on a high.
The Session - SPOILERS
PLEASE DO NOT READ IF YOU INTEND TO PLAY THE MISSION YOURSELF (and don't want to have it spoiled of course).
The players instantly began searching, eager to stick to their primary objective. Thanks to Brother Ivar's super-wolf senses they tracked from the crashed shuttle to the ambush site where the Magos had been attacked. Despite no one having Tech-Use I allowed a half-characteristic untrained test, through which Brother Invictus showed why Ultramarines are named such - passing incredibly.
They shared the datafile and were beginning to move out in the general direction (once again found by Brother Ivar using his Space Wolf senses)
when a pair of Winged Tyranid Warriors descended from the sky to attack them. I was interested to see how powerful the Warriors would be, so I only sent two. While Brother Astramael charged toward one to engage it in hand to hand, the other two Marines engaged at range. Initially shooting seemed to do very little, only Brother Ivar's kraken rounds really producing any damage. Brother Astramael in combat was a different matter and he matched the Warrior brutally.
It was at this point that I rolled a sickening success for one of the Warriors' rending claw attacks against Brother Astramael, followed by Righteous Fury. This would have left him a near cripple - however I realised I had neglected to remind the players about the uses of Fate Points so I allowed Brother Astramael to retrospectively use a re-roll, which he did to parry the potentially fatal attack.
Meanwhile the other Warrior had closed on Brother Ivar to eliminate the source of the kraken rounds, while Brother Invictus seemed to be able to achieve little. I had described that as the Warrior waded into combat with Ivar, he had folded his lower gun arms behind his back in the direction of Invictus. Rather than see this as a threat, Invictus remembered a clearly very obscure part of the Codex Astartes and reasoned that the large barrel of the Death Spitter would make the perfect hole for a krak grenade. He charged forward and after failing to time his departure correctly would also catch some of the blast if he succeeded - which he did. Krak grenade lodged firmly inside, the blast crippled the Warrior, while Invictus escaped with a few wounds.
While this was happening Astramael was engaged in an epic struggle which he eventually won - hacking the Warrior to pieces completely independently - and loving the Blood Frenzy solo ability! Invictus held down the Warrior, while Ivar moved in to deliver a killing blow with his combat knife. Alas, a fumble saw the knife swallowed by the Warrior and Ivar kicked away. Invictus used his feat of strength ability, to snap the Warrior's neck, killing it and allowing the knife to be fished from the remains.
The group healed their wounds and proceeded toward the compound nearby. Once they saw the Imperial Guard and Commissar about to be swept aside by the Hormugant Horde and Tyranid Warriors they had to make a decision. Ivar and Astramael were all for letting the Guard die, but Invictus decreed they were to step in. Ivar and Astramael moved to the rear to attack the Warriors, while Invictus moved amidst the Guardsmen to face the horde and inspire the men.
Once again Astramael proved his combat mettle, slaying his Warrior foe. Ivar unleashed his kraken rounds with fully automatic deadliness, slaying his Warrior foe. Meanwhile Invictus held the line against the tide of Hormugants - slaying most with his frag grenades, then bolt pistoling the remains.
Most of the Guard squad was killed in the encounter, but 2 men and the Commissar remained. The Squad questioned these survivors about the location of the Magos. The Commissar relayed how he had seen the crashed shuttle and sent a squad to investigate - they reported that on the way they had been set upon by criminals escaped from the local refinery works who had forced the Guard to retreat - shortly after the Tyranids began attacking the compound.
The Squad sent the survivors to secure the Communications Relay ready for extraction later, while the Deathwatch went to the Primary Refinery Unit to confront the criminals.
They rushed at full pelt, reaching the mag-line only to be ambushed by two hordes of Hormugants. One rising up from the sands around them, while the others lay perched on top of the mag-line. Invictus used his last grenade to great effect against the sand-horde, while Ivar used his bolter to blow apart one of the supports holding up the mag-line. It partially collapsed, killing many of the horde on top of it, before the tightly clumped survivors were set upon from above by Astramael jump packing into the sky to drop a frag grenade into the centre of their mass obliterating them. The remaining few were easily killed.
As the Deathwatch reached the Primary Refinery Unit, they could see two hulking beasts. The Pyrovores were coating the building in thick green toxic flame, attempting to flush out the humans inside. As Astramael charged, eager for a new foe, Ivar and Invictus each fired full automatically and killed their targets in a single salvo, leaving Astramael without his prize.
The Deathwatch pressed on inside the building, up toward the centre office work space. They crashed through the crude barricade to encounter a room filled with desperate men pointing weapons at them. They demanded the location of the Magos. The leader of the criminals wanted an escape from the planet. Brother Ivar stepped forward and shot the leader through the head, before pointing his bolt pistol at the nearest criminal and demanding to know where the Magos was. After the criminal told him, Ivar was not certain they were telling the truth - so fired again. As the next criminal reiterated the information - Invictus reassured Ivar that they were indeed telling the truth.
As the Deathwatch left the room, several criminals dashed toward them begging them to save them. The Marines flung these traitors back into the room, before barricading the doors and leaving for the location they had been told: the transport station.
They moved at pace down the mag-line, before sighting three Winged Warriors circling in a patrolling fashion overhead. Reasoning they did not want to waste the time to conceal themselves, they carried onwards chancing they would not be noticed. The Warriors were eagle eyed however and flew over the Marines blasting them from the air. Astramael dashed ahead, aiming to reach the transport station as soon as possible, while Ivar and Invictus engaged a move-fire support, fire support-move system. Despite the primary design of this being to disrupt rather than kill the Warriors, their shooting proved so keen sighted that the Warriors were blasted out of the sky by the time Astramael reached the transport station.
Astramael burst inside, his Space Marine senses noticing the concealed Hormugants before the concealed creatures could pounce. After gutting two, he lost his chainsword and was forced to fight with his bare heads as Ivar and Invictus ran double time to the transport station. After a series of unfortunate events, Astramael was wounded and the relief his brother Marines brought was welcomed.
After searching the transport station they came across a hidden smuggling den - following it down to the human trafficked cages. In one of these cess pits was the Magos - wounded and malfunctioning but still alive.
Once they had convinced him of their Imperial nature, they planned to move to the Communication Relay as soon as possible. They were frustrated with his refusal to be aided or carried but continued onwards as fast as they could toward the Comms Relay.
As they climbed the brow of the hill, the Comms Relay now in sight, 5 dark shapes appeared in the sky as more Winged Warriors closed in. Ivar activated the locator beacon ahead of time, while Invictus tried to reach the Guardsmen on the Comms Relay. Astramael meanwhile had decided that the Magos was more trouble in this weakened state than he would be dead. So with their Primary Objective of the datacore in mind, he drew his chainsword and cleanly (as cleanly as possible) decapitated the Magos, before grabbing the remains and jump packing ahead of his brothers to reach the Comms Relay as quickly as possible.
Ivar and Invictus assumed the same role as before, trying to pick the Warriors out of the sky before they could attack Astramael and the datacore.
Once again the Emperor smiled on the two Marines and their shooting saw the final Warrior fly wounded back toward the crashed shuttle.
As they reached the Comms Relay they saw the Guardsman and Commissar waiting. The Commissar was holding his binoculars, hands shaking as he passed them to Invictus. In the distance came a gargantuan horde of Hormugants, supported by half a dozen Warriors and with a Hive Tyrant looming behind them. It would not be long before they arrived.
The Deathwatch set about making the position as fortified as possible. Astramael flew out with the remaining grenades to create a booby trapped area leading to the Comms Relay, while Ivar decided to hold the ramp that led to the top of the Comms Relay which Invictus would snipe down from. The Commissar and one Guardsman would remain with Ivar, while the final remaining one would look to the skies for their Thunderhawk extraction ship.
As the horde closed (I played music ) the hidden grenades reaped a heavy toll on the unsuspecting Hormugants and even some of the Warriors. As they neared both Invictus and Ivar mowed down swathes of Gaunts, before a Warrior came barrelling toward Astramael who had planted a stand at the foot of the ramp.
At this point Astramael channelled the spirit of Sanguinius as he held the gates of the Imperial palace. (After being given a sickening number of tests to pass - and passes them all with flying colours) Astramael's eyes rolled into the back of his head, he floated upwards without activating his jump pack. He grabbed the throat of the Warrior, avoiding its blow, before carrying it up into the heavens while choking the life from it. Astramael's arm swung round in a series of wide arches, before releasing the Warrior back to the ground in a flurry of blood and fire. The Warrior shot through the oncoming horde, decimating and disorientating the Gaunts. Astramael's body plummeted to the ground, unconscious from the event. Ivar leapt forward, mowing down the few Gaunts who had been close enough to attack but had avoided the onslaught.
Ivar dragged Astramael up the ramp, while the Guardsman and the Commissar attempted to hold back the oncoming Tyranids. The Guardsman was turned to mush before Ivar could hand off Astramael to Invictus and turn back the attackers.
The final Guardsman called out in triumph - the Thuderhawk was here! Before his words died in his throat as he screamed in horror. Rather than their salvation, the enormous shape was actually the Hive Tyrant! The creature let out a psychic scream which melted the mind of the unfortunate Guardsman.
The Commissar strode forward, plasma pistol readied and fired at the Hive Tyrant shouting oaths to the Emperor. As the shot hit the chest of the Hive Tyrant, the creature exploded! Mystified momentarily, the answer and their salvation was provided as the Thunderhawk emerged from the mist behind the Hive Tyrant, its weapons smoking.
The Marines climbed aboard, Commissar and Magos remains in tow, for everyone to breath a huge sigh of relief, victory and good times