To continue on from what Lunkhead said above, the difference is in execution. When drawing from a source to influence your chapter, there's a fair divide between being 'influenced' by the material and copying wholesale bits of lore and throwing it into your chapter.
As a matter of fact most of GW's original legions are really good examples on how not to show influence. Some of them get away with it more these days through some work and better writers to expand upon them (such as the Salamanders and White Scars, though BL is inconsistent at best), it's not all been fixed. the Space Wolves and Raven Guard were and are still essentially power-armoured versions of their inspiration, Viking werewolf-marines and Poe-Marines respectively. Then you've got the Mongol-Marines in the White Scars, the Roman Marines for the Ultramarines. Hell even newer chapters like the Minotaurs and the Iron Snakes are really on the nose in where they draw their cultural inspiration from.
Now I'll let it be said it's not all bad. You can have a solid influence and wear it on your sleeve, that's no real issue, so long as you're not constantly beating the reader over the head with either references to the material or stretching 40k lore to shoe-horn in your concept.
What you're looking to do here is not necessarily subtle. Astartes aren't subtle and neither are their chapter cultures and societies.
What takes you away from all this is the same thing in any good story, suspension of disbelief. You lay it on just thick enough to differentiate your 8 foot, angry walking tanks from the other guys, while also having the reader believe they fit within the 40k universe as a whole.
Funnily enough, GW being so unbelievably heavy handed with the original legions means you've got a hell of a lot more room to work with here in that regard.
Now, to bring this into direct relevance to you, there are a couple of things.
One- your references to what is at the moment a piece of iconic gaming pop-culture means you actually have far less wiggle room for suspension of disbelief, so I'd lighten the direct references like 'The Bastion'. It doesn't have to be a sphere it doesn't have to operate in even remotely the same way, people will still get the inspiration if you word it right.
Secondly am really unsure as to why you'd waste the fighting potential of an entire chapter of Space Marines to 'study' an alien artifact. Leave that to the AdMech and Inquisition sponsored acolytes. However if they were there to secure the region and project that stabilizing presence to reduce potential risk to the artifact and where it's situated? Absolutely.