I've been reading "No Surrender" and a few notions come to mind. I'm more likely to use it in Rogue Trader or Deathwatch so this may influence my thinking.

1. Space marines. What would be a reasonable number to seize Lycurgos, whether by themselves or with support of regiments? I've notions about at least one company supported by IG or equivalent.

2. Nova Cannons. On p63:

As the star fort also included these
weapons on two of its docking arms, this provided the station
with an added tactical advantage.

But...

Can a star fortress really make use of nova cannons? It doesn't have much in the way of maneuverability after all. Is it reasonable to leave the cannons there or are they author mishap?

I'd run a Space Marine game of No Surrender as a single chapter game, dedicating perhaps one company of Battle Brothers - likely the ninth of a chapter.

100 Space Marines is a pretty good number for overwhelming a Star Fort on their own, and it adheres reasonably well to the Codex. Unless you're rolling out the Black Templars, in which case go wild lol.

If you don't have any chapters in mind, I recommend either a Blood Angel, Ultramarine, Space Wolf or Salamander set up due to all having notable experience operating in Space Hulks or the purging of infestations.

Cheers. I got thinking about the composition of Space Marine boarding actions in general on the Deathwatch board: http://community.fantasyflightgames.com/index.php?/topic/135053-boarding-actions/

What I may end up doing in running "No Surrender" in a Rogue Trader game, where the dynasty has started an alliance with the Star Panthers (a custom Raven Guard successor chapter specialising in siege warfare). Otherwise, Lycurgos might appear in a Deathwatch game.

Can the Star Fortress make use of nova Cannons, sure, as a space station is not a transport raider or firgate it may fire in a 270 Degree arc (page 219 Rouge trader Core Rules book), having two means that there is no blind spots; the station is stated to have a massive manufactorum so its possible that it producess its own shells.

The way I designed the lycurgos was as 5 different ships (for firing arcs), 2 arms have nova cannons in the prow, a pair of Macrobattery Broadsides on the port/starboard and docking arms; the other two had Lance Batteriesin the prow, another pair of Macros on the port/starboard and docking arms. The hub held most of the supplementals but had 4 'side' slots filled with Landing Bays;

at the best of time a attack ship would be facing a Nova, a Lance, two Macros and what ever fighter/bombers where still in the air

ok this was for a high level Black crusade game and was ment to be a challenge so scale it as you want

I'd run a Space Marine game of No Surrender as a single chapter game, dedicating perhaps one company of Battle Brothers - likely the ninth of a chapter.

This is entirely optional, but for a GM who wishes to stick to codex background as much as possible I'd recommend something between the 2nd and 5th Company.

6th through 9th are Reserves, and they rarely if ever deploy on their own - instead their role is to provide support for the Battle Companies in the form of additional infantry elements and vehicle crews, as well as a recruitment pool for replacing casualties. Most Chapters base their combat operations around one Battle Company reinforced by elements from the Reserves.

Just bringing this up as it may feel like an interesting organisational element for Marine games - plus, some people like playing close to GW's background, yet may not be aware of this detail. As mentioned at the beginning, this is just one way to envision the setting, and even in GW's own fluff not all Chapters may adhere to it (pretty sure the Wolves don't care, for example).

My 2 cents on nova cannons. While stations are easily big enough to carry them, just look at a Ramilies next to a cruiser @#%$, traverse would be a huge issue. Nova cannons are large enough to count as structural on a five km long cruiser, and require much of their length to be surrounded by hull as gravitic impellers are both large and fragile. Turning a mile long tube deep in the structure of your station is a bit much to ask for. Rotating the station itself would take less hassle and be a pre existing feature in any functional station.

As for arcs though, you have decent options. I'm taking it that a planet covers most of one firing arc. Putting the guns on opposing arcs would allow you to cover 90° in different directions but you risk having one gun pointed at the planet a lot. Side by side arcs allow you to cover most approaches with one gun or the other, a 180° arc while the planet blocks a lot of the approach from the other side. Both guns in one arc requires the station to turn a lot but the continuous bombardment will roflpwn pretty much one cruiser every other turn.

The fine details are up to you.

Thanks for more views everyone. I'm currently inclined towards having the nova cannons side by side, because of the traversing issue.

As for marines, a notion I've been playing with is a roughly company sized group. Mostly 4th company, with the few squads of a heavily depleted 8th company, and a few 1st and 10th company squads to round it off.