It's an old joke that every new Call of Duty game is just like the last, but if you say that about Black Ops 4 (or "IV"), chances are you're not actually paying attention. This game marks a major departure for the series, in that there is no focus on a single-player campaign (though solo elements still exist). Instead, the game's developer pads the mainstay multi-player modes with Call of Duty's first take on the Battle Royale genre.
Like that old Call of Duty joke, it's also become somewhat comical that nearly all game developers now want to integrate Battle Royale into their games. Who doesn't want Microsoft Solitaire: Battle Royale Edition? That doesn't actually exist, but would it surprise you if it did?
With Black Ops 4, it feels like Treyarch understood the issue of copycat BR games coming out left and right. The general player consensus is that most of them are not doing enough to differentiate. While the BR mode in the latest CoD will look familiar to anyone who's played PlayerUnknown's Battlegrounds or Fortnite, Treyarch made sure BLOPS 4's was going to leave an impression.
Refinement was a major focus for CoD's BR take, with everything from the fluidity of gameplay to vehicle physics being improved over even the biggest titles in the genre. One way Treyarch helps differentiate itself is by implementing perks into the gameplay -- temporary buffs that aid players, but don't give a massive advantage.
Another simple, but really cool take on things is loot tiers. Whereas Fortnite color grades its weapons, BLOPS 4 simply highlights rare weapons with a gold tint. Whether this highlighting is a good thing or not really depends on your taste, but if any weapons need to be highlighted, it's good that only the best of the best get the treatment, to keep things simple.
Another important distinction between BR in other games is that Blackout's map is smaller than the others. That will lead to faster-paced gameplay, and likely shorter rounds (unless you happen to be a star player, of course). We can't ignore the fact that this BR take also includes zombies. It's not a major part of the mode, but rather something you'll simply encounter in certain parts of the map, adding yet another twist and unique flavor.
Overall, this seems to be a great initial showing from Call of Duty, and one that's going to be iterated on over the course of the next year, as has become standard fare for the series. How much of the post-launch love will go to the Battle Royale mode remains to be seen, but if it proves popular enough, it's sure to receive some extra attention.