Okay kiddies, It's time for us 'not 40k' players to give you all some reference about space marines.
First things first, After the horus heresy, the space marines were removed from their place of power (for damn good reason) and had two major checks and balances placed on them. Number one is the Imperial Guard (who can still crush entire chapters under sheer numbers) and Number Two is the Imperial Navy (which are better equipped, better led, and have vastly greater numbers).
In the current fluff, space marines are surgical strike teams. In everyone's favorite 40k, they do extremely well, because this is the scale they were MEANT to fight with greater focus. In Epic Armageddon, they function very differently, being able to focus huge power in small areas, but can be overwhelmed by other enemies. It takes a VERY skilled commander to win with Space Marines alone in Epic.
In BFG, The punishment for the horrors of the Heresy is their removal from the running of the empire and their restrictions to glorified troop transports as space craft. It is testimony to their great skill that they use them in space combat with such effectiveness. When it comes to pure ship destroying firepower, they must rely on their escorts (which are amazing to begin with).
This Leaves us with some facts established in the genuine fluff (codex's only, none of the black library fanwank)
1. The Imperial authority in space is the Imperial Navy. In every engagement, they should have an advantage against a space marine commander. Space marines must rely on their unorthodox strengths to win against such an opponent, because weapons alone WILL NOT SAVE YOU!
2. The Space Marines are the authority on planetary assault and exterminatus for the Imperial fleets. They are AMAZING at it, and should reflect this in their rules.
3. Lances are one of the major balancing factors which the Imperial Navy and AdMech keep a very close eye on. The Navy does NOT like the Nova frigate, since it threatens their principle advantage against the Space Marines and the threat of another Heresy. These should never be common.
4. Space marines are perfect for hit and run attacks and boarding actions. They should always be amazing in such circumstances.
5. Space marine fleets should NOT have access to imperial navy ships as a -normal- part of their fleet. Reserves, yes, normal part, no. This goes for Chaos ships as well, aside from the venerable battle barge listed in the Forces of Chaos list. I don't care what your black library says. It's not common, and the Imperial Navy would NOT stand to allow any chapter to hold on to battleships, even if it was 'a gift from the emperor' (I am looking at YOU space wolves!). AFTER the Heresy, they would be more likely to blow it to atoms then let a less-then-trustworthy chapter hold such incredible power. Also, they would not field such a rare treasure in such small scale engagements that we are throwing down.
6. Space Marines get their skill from discipline and constant training. This does not equate to a high attack rating however. They should have superb leadership, but a poor attack rating.
7. Space Marines -do not follow orders- from Inquisitors. They can go along with their plans, but no marine has to follow the orders of an inquisitor. Grey Knights work with the Inquisition because it suits their purposes.
8. On this scale, chapter differences mean squat in boarding actions and leadership values. On average, 2000 points of Space Wolves will cause JUST AS MUCH CARNAGE as 2000 points of Ultramarines, Blood Angels, Blood Ravens, Space Sharks, Astral Knights or Rainbow Warriors. We are fighting on a scale that can BARELY be converted to 40k scale. This is why there are no fancy rules per chapter.
9. No single ship in the Space Marines list should be more powerful overall then an imperial counterpart. Barges cannot be stronger then Battleships, Strike Cruisers cannot be more powerful then cruisers. Venerable vessels and escorts are the ONLY exception to this rule (as escorts are allowed to carry combat level firepower and venerable vessels hail from an ancient time where they were permitted long range firepower)
10. Bombardment cannons are ship combat weapons by accident, far less then purpose. They were meant to bombard fortified enemy positions on a broad and messy scale. It is a sign of the incredible power of marine gunners that they can be used against enemy ships. They should not be so potent as they are against ordnance though
![Tongue :P](http://www.specialist-arms.com/forum/Smileys/default/tongue.gif)
11. Thunderhawks are good, but not super-good. They are just-fine-where-they-are.