Warhammer (Fantasy and 40k)

The tabletop is lidicrously expensive. Good armies for 40k can run literally thousands of dollars. Depending on the unit, just one figure for 40k on the GW store can range between $50 and $300. Keep in mind for a 2000-point game (probably the most commonly played value) you'll be deploying several dozen figures regardless of army.

As for who can beat the Tyranids, as far as fluff goes, each faction is powerful enough (or has the potential to be powerful enough) to defeat all of the others. IMO I don't see any plausible scenario where the Tau would defeat the rest but GW insists that they're all more or less even. The other factions are all pretty fair though. The Imperium has a fighting chance now that Guilliman has returned, and if they can recover any other Primarchs then they will definitely get a leg up, and the Mary Sue Samarinda introduced in 8th Ed. are as strong as Thunder Warriors without any of the drawbacks (I hate Primaris Marines and whoever invented them), giving them arguably the best infantry. If the Emperor returns (or gets better, rather, since he technically never left), then they just win. If the Orks were capable of uniting for more than 30 seconds and launched one massive WAAAAAAGH! they could potentially scour the entire universe clean if they wanted. Chaos, is Chaos, they're all but innumerable and unstoppable if there's enough emotion and worship going around. Numbers are the Tyranids' entire gimmick, and they're potentially infinite beyond the galactic rim. The Necrons are so absolutely powerful compared to all of the other races that the only reason they haven't taken over yet is that most of them are in a coma (and it took nothing less than a galactic-level mass extinction to put them to sleep) and god help the rest of the Galaxy if the C'tan are restored to even half of their former power, they could murder the shit out of the Chaos gods if they were at their full power again.

Yeah, the only reason that the Tau haven't been obliterated by the Imperium is because the Imperium just can't be arsed to do it, they barely register on the Imperium's radar.

The C'tan and the Old Ones are separate entities. The C'tan, also known as Star Gods, were once primal, formless energy beings possibly as old as the galaxy itself (if not the universe) who met the ancient Necrons (then known as the Necrontyr) and were given physical bodies made of living metal. The Old Ones are, at their most basic, hyper-advanced pan-dimensional reptile aliens. They developed the Webways, which the Eldar use for transportation, as well as the Eldar themselves (also the Orks). The Necrontyr waged a war with the Old Ones because the Necrontyr were jealous of the Old Ones' vast, practically-endless lifespans (since the Necrontyr evolved under an extremely volatile star that made their lives short and painful, the prospect of immortality looked good to them) and the Old Ones refused to share their technology. The Necrontyr, as one could expect from a species of decrepit cancer patients, got thoroughly trounced by the Old Ones and retreated. In their home system, they noticed a creature hovering around their star, a C'tan (newer lore suggests that the C'tan was at the star pretty much from the start of Necrontyr development and was even the reason why the star was so shitty). They made contact with the C'tan who offered them a way to defeat the Old Ones. The C'tan entities feed off of energy, hence the star-eating, but they noticed that they can also feed on, for lack of a better term, life energies, and some emotions like fear. So, the C'tan manipulated the Necrontyr and their hatred of the Old Ones to find a new, better source of food. Also the C'tan are just massive assholes and are actively malevolent. So, the C'tan convinced the Necrontyr to construct them the living metal bodies, and offered immortality to the Necrontyr in the form of living metal bodies of their own. This the now-robotic Necrontyr, properly known as the Necrons, were enslaved by the C'tan and used as tools, weapons with which to spread fear and terror throughout the galaxy so that the C'tan may get at that rich, sweet life energy. The Necrons utterly demolished the Eldar and Orks sent their way by the Old Ones, and the combined forces of the Necrons and the C'tan drove the Old Ones to retreat into the Webway. This war was known as the War in Heaven, from Eldar mythology. Ultimately, the Necrontyr were not quite as mindless as the C'tan had initially believed, with some Phaerons and other higher-ranking individuals retaining enough independence to spark a rebellion against the C'tan. The C'tan, due to a combination of simple surprise as well as being fattened on life energy, were overthrown by the Necrons, their living metal bodies shattered into shards, which were taken by the Necrons and locked away. The Necrons, now in th 41st millennium, have been known to utilize these shards in combat, for the C'tan, greatly diminished they may be in their present form, are still horrifically powerful, capable of routing and utterly destroying entire armies by themselves.

The C'tan in their prime rivaled the Chaos gods, and a case could be made that they were actually stronger than the Chaos, gods at their peak. In fact, calling them sort of anti-Chaos gods wouldn't be too off the mark. They despised the Warp and creatures derived from it, to the point where they devised a plan to completely cut off the galaxy from the Warp altogether, evidence of which can be seen in the form of the Pylons on Cadia, that keep the Eye of Terror in check. The C'tan weren't able to complete this plan before their downfall, which is why only Cadia contains these pillars.

As for the Old Ones, it's not known whether they died in the Webway, if they left the galaxy, or what. It's theorized that the Slann, a race of reptilian semi-humanoids found in the 41st Millennium, are devolved from the Old Ones, but no confirmation from GW. Though the Old Ones are gone, their influence is felt to this day in the form of the Eldar and the Orks, as well as the Webway, which the Emperor of Man was almost successful in replicating for humanity's use. Speaking of the Eldar, you can almost thank the Old Ones for the birth of Slaanesh, since the Eldar were the ones responsible for that.

The best Space Marine chapter are the Salamanders, and anyone who says otherwise is simply wrong. They come from a planet that is as close to the Biblical Hell as one could get, and despite being one of the smallest chapters (due to massive losses in the past and their homeworld, Nocturne, being so cartoonishly dangerous that they can't replenish fast enough), they're one of the most dangerous chapters to face in combat, and they're arguably the most morally upright people in the Imperium, going out of their way to interact with regular citizens and offer assistance whenever they're off-duty (as "off-duty" as a space marine can be, anyway), and are one of the few chapters (possibly even the only chapter, now that i think about it) whose marines keep in regular contact with their families. Also they have the most metal name of any other Marine chapter. Not "Salamanders", but their original name, the Dragon Warriors.

It's less that Necron weaponry "goes through" armor, more than it shreds it apart, atom by atom. To my knowledge, there isn't any solid material that can withstand Necron gauss weaponry. I also wouldn't go so far as to say that melee combat beats out ranged. Power weapons are certainly extremely powerful and can take out pretty much anything in just a handful of swings, but every faction has a handful of projectile or energy weapons that can deal extreme damage. Tau plasma rifles, for example, are arguably the most dangerous main infantry weapon in the setting, compared to bolters and lasguns, really only beat out by Necron gauss flayers. Plasma weapons in general are heinously effective in combat, assuming they don't explode in the user's face (though that applies more to the Imperium, Tau plasma weapons are very efficient).

And yeah, the Necrons are severely OP, even by 40k standards. Like I said before, the only thing keeping them in-check is that 90% of them are in a coma. They have arguably the best weapons, and are functionally immortal due to the self-repairing robot bodies. Aside from them being asleep, their biggest weakness is that the average Necron warrior has practically no intelligence and must be led by a commander to have any real effect. The Eldar (counting both the Craftworld Eldar and the Dark Eldar since they're the same species) have been extremely reduced in number from the time of their old empire, yes. The Craftworld Eldar in particular are very, very few in number compared to the other groups. Their leg up on the competition is that, aside from the Necrons, they're by far the most technologically advanced race in the galaxy at the moment and suffer relatively few losses due to both this, and the the fact that the older Eldar Warriors can have literally thousands of years of combat experience, making them extremely skilled fighters. Also they are the only ones with reliable access to the Webway, which is infinitely better as a means of transport than the Warp. They also have access (admittedly limited) to their gods, who haven't all been killed off (yet), in the form of the Avatars.

The space marines' implants are not what sever family ties, that would be the indoctrination and brainwashing that most of them go through during their training. I don't remember what makes the Salamanders so unique in this regard, but they do maintain communication and ties to their old family and friends. Really, it depends on the chapter in question. Some just took to the indoctrination better than others (it also depends on the geneseed from which the marines are descended) as well as the culture from their homeworlds. Ultramarines, for example, being from the realm of Ultramar (a very orderly place with strict adherence to protocol and rules) are very devoted to the ideals of the Imperium, and follow the Codex Astartes to the letter (it helps that Roboute Guilliman, their Primarch, actually wrote the Codex himself). Compare them to the Space Wolves, who are more in-line with jovial beer-slinging viking brawlers than proper "marines" (though not all Space Wolves are like this, they have some variance within their chapter, but the average Space Wolf is likely what I described). Compare THEM to the Soul Drinkers, who outright abandoned the Imperium and effectively turned to piracy ever since the Inauisition declared them Excommunicate Traitoris due to their higher susceptibility to Chaos corruption. The Soul Drinkers are loyal to the Emperor himself and the ideals that he stands for, but the Imperium, as a governing body, can go fuck itself and burn in their eyes.

The Skaven are probably my favorite army in WFB. Good ol' Chaos is... good too.

Space Marine was good, if a little repetitive. RP for 40k sounds like it would be pretty fun, you have an absolute ton of variety in the different marine chapters, guard regiments, Craftworlds, etc.

Ditto on Total War though. Creative Assembly has said that they plan on making TW:W2 more story-driven, so hopefully they can deliver.

Probably Space Hulk: Deathwing that you're thinking of. It's basically just Space Hulk, but as a first person shooter instead of a board game. It's also a horrible game. That MMO you're talking about may be Eternal Crusade, which was advertised as an MMO but ended up not an MMO.

How is Battlefleet Gothic: Armada? It looks pretty interesting, and I've never played a galleon-style combat RTS like it before.