The setup for this scenario is set out pretty clearly in the blurb:
“The Frozen Reaches throws the Explorers before an impending Ork invasion as they work to save the planet of Damaris... Use all your charm and influence to prepare a planet’s defences as the Ork fleets close in on Damaris. Fight the xenos in space aboard the bridge of your starship, or meet the bloody Orks in brutal hand-to-hand combat on the ground! The choices you make ensure success, or guarantee defeat. Choose wisely, and reap the rewards of your victory.”
So the explorers have a job in three acts, organise and prepare the planet, fight the siege, then take the fight to the Orks to end the threat once and for all. It’s a nice idea - to have the characters directly involved in a massive global siege, able to spread their influence to different parts of the fight to tip the balance. This is achieved through a series of structured missions, and a bespoke system for resolving each aspect of the siege, modified by the actions of the characters. That seems pretty cool, and a different approach to the Star Trek style episodes of Lure of the Expanse, promising to really invest the characters in the richness and complexity of a planet. However, in my opinion the book fails to adequately deliver on its potential.
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In addition several other Rogue Traders are described as having responded to the planet’s distress call, and as their ships are reasonably powerful, it does seem unlikely that the explorers would actually be anything but bit players in the forthcoming events. However, the characters are expected to discover the motives of the other Traders, and merge them into an impromptu coalition. So the scenario seeks to make the planet worth saving in terms of future profit for the explorers, but at the same time arranges events so that a Rogue Trader and their ship could significantly influence the outcome of the battle, and this comes at the expense of some in-game realism.
This could have been addressed if further details were provided – perhaps the Imperial Levy has recently been particularly heavy and stripped the planet of soldiers (picking up on the thread of simmering ambitions for independence presented elsewhere in the scenario)? Perhaps there is an evacuation already underway, and the Imperial fleet is en-route, but the Explorers have a critical role to play in the interim. Unfortunately there is simply not enough detail provided to facilitate this, and the GM is left to find their own meaning in the void.
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“Just what really resides in the stasis casket will be revealed in future instalments of the Warpstorm trilogy…”
To conclude; The Frozen Reaches provides a fairly innovative and interesting set-up for the characters, allowing them to engage with a specific planet, and play a significant role in an epic Ork siege. However, the GM is not furnished with enough detail to really bring any particular aspect of the scenario to life outside a narrow railroad of expected PC actions, and accordingly a large creative load is put on the GM to help this scenario deliver on its vision. We had fun playing this scenario, but some characters (like the Navigator) were significantly disadvantaged in their potential to be useful, and the final conclusion, with outside aid coming from the Eldar, feels like an unrewarding way to repay the efforts of the characters, and their persistence with the relentlessness of the Ork attack.