Warcraft was supposed to be a Warhammer fantasy video game adaptation. Actual Warhammer and it's Sci-fi variant are played using 28mm miniatures which people assemble and paint themselves.

As others have said, it's an expensive tabletop wargame for adult children to scoot their army man toys around while pretending to be generals. Here's one of my inquisitors. It's about an inch and a quarter tall:

Unfortunately, it's attracted a lot of chuds because it takes place in a dystopia. It's where the term "grim dark" comes from, since one of the game's tag lines is "In the grim darkness of the far future, there is only war. An eternity of carnage and slaughter, and the laughter of thirsty gods." They ignore how the game was a parody of various sci-fi franchises and taking the piss out of fascists, insisting on taking it all very, very seriously.

As far as the game itself, it's currently in 10th. Edition and I prefer older versions of the game. And again, it's expensive. Cheaper than skiing or cars, more time consuming than video games. Other non-Games Workshop miniature games are far less expensive. You can usually get models from $0.50 to $2 each from most manufacturers. Games Workshop charges anywhere from $5 to $50 each for their equivalent infantry models. For comparison, I got 100 of these soviet infantry models for $25 total and $15 of that was shipping:

They're only a few millimeters shorter than the model I showed above. Here's a monster I'm working on made from $1 animal toys and modeling putty/clay:

Luckily, a lot of people who actually play the game are friendly and welcoming (at least where I'm at). Chuds get chased away real quick because of their shitty, sore loser attitudes and lack of creativity.

It's a tabletop game played with absurdly expensive plastic miniatures, but there are a ton of video games from the franchise now, and I would bet that the majority of online warhammer fans have never even touched a miniature before. (not that I blame them, it is a huge waste of money).

"Warhammer" is fictional fantasy world with fantasy elements like dwarves and elves and french people, and warhammer 40,000 (or 40k) is a sci-fi fantasy that was created as a parody of absurdly grimdark sci-fi where everything is shit for everyone all the time, but like any popular parody, people unironically enjoyed the setting and now the vast majority of content related to the franchise takes the grimdark stuff 100% seriously.

God, I fucking envy you so much. I wish I never heard of it.