Over 45 million people are playing a bizarre shooter that pits 100 players against each other in a fight to the death - here's what's going on

The first thing you do in "Fortnite: Battle Royale" is jump out of a purple flying bus and parachute down to an island. The island is full of distinct regions, and it's littered with resources: Guns, explosives, med packs, shields, and various materials (wood, brick, metal).

With nothing other than a pick-axe, you desperately need resources to survive. This is a nearly direct mirror of the experience in another popular, Battle Royale-style shooter: "PlayerUnknown's Battlegrounds,"

But there are major differences right off the bat.

Rather than simply picking up weapons and healing kits, "Fortnite: Battle Royale" also has a construction element to it. Thus why you're picking up materials — stuff like wood, brick, and metal. Alternatively, you can use your pick-axe to mine the materials yourself, like you would in "Minecraft" (as seen above).

The world is destructible, so with every swing of your pick-axe you'll wear down whatever object you're striking — whether it's a tree or a brick wall.

There are loads of parallels between the two games, but "Fortnite: Battle Royale" is immediately distinguished by this crucial difference.

In 2017, when "PlayerUnknown's Battlegrounds" was dominating the conversation and drawing millions of new players every day, the big question became, "Who is going to copy this format and do it bigger?"

Epic Games answered that question in September 2017 with "Fortnite: Battle Royale," a free mode for its "Fortnite" game based on the concept of "PUBG."

Better than just being free, "Fortnite: Battle Royale" was available on Xbox One and PlayStation 4 months before "PUBG" could get there. Great for players, no doubt, but not a great look in terms of perception. Was Epic Games rushing out a copycat mode to beat out the competition? More awkwardly, the software that created "PUBG" is made by none other than Epic Games — the Unreal Engine. It looked like Epic Games might be undercutting its own client and copying the client's idea.

There was even a press release from Bluehole Studio, the company behind "PUBG," criticizing Epic Games. "We are concerned that 'Fortnite' may be replicating the experience for which 'PUBG' is known," Bluehole vice president and executive producer Chang Han Kim said.

But actually playing the game demonstrates relatively quickly why "Fortnite" is doing something different.

"PUBG" is so excellent because it's suspenseful. Each life matters distinctly — matches can last as long as 30 minutes as you carefully creep around the game's massive world. Dying from a sniper after 20 minutes of a match because of a foolish move can be devastating.

Each sound in "PUBG" has impact. Was that an enemy? How close is that gunfire? Did someone open a door? 

"Fortnite" is excellent because it takes that same formula and throws out all the weight. 

If someone starts shooting at you in "Fortnite: Battle Royale," you can immediately conjure a wall from the ether in front of you. Many matches end in surrealist madness, as players erect massive towers out of nothing as a means of protecting themselves from the last few remaining players — all while taking the occasional shot at their enemies. 

You can actually watch it all play out even if you die, as there's a spectator mode built in to the game. That I've sat and watched several games play out after my own death is a testament to how entertaining "Fortnite: Battle Royale" is.

Matches in "Fortnite: Battle Royale" are pretty quick, often lasting 10 or 15 minutes at most in my experience. That helps to make it a bit less frustrating when an enemy comes busting through the ceiling with a shotgun, which happens every now and again.

It's easy to hop back into a new match and keep the fun going, in a way that's reminiscent of playing "Overwatch" or "Halo" online multiplayer.

I can easily jump in for a few matches before bed in "Fortnite: Battle Royale" — something I'm unlikely to do with "PUBG," which requires a lot of time and an emotional investment. "PUBG" is stressful, whereas "Fortnite: Battle Royale" is silly. I don't mean that as a knock against "PUBG," of course — it's amazing that "PUBG" is such a vehicle for emotional response. But sometimes I don't want to stress out right before going to sleep, and "Fortnite: Battle Royale" offers a nice alternative.

"Fortnite: Battle Royale" is a free game. It costs nothing to play online, and there's no limit to how much you can play. Even the version on Xbox One and PlayStation 4 is free.

The way that the game's maker, Epic Games, earns money on "Fortnite: Battle Royale" is through so-called "microtransactions." In the case of this game, they're not so micro. Buying virtual currency for use in-game starts at $10, which gets you 1,000 "V-bucks."

You could use that money to buy stuff in the item store for your character, ranging in price from 500 ($5) to 2,000 V-bucks ($20). Or you could use it to buy the game's "Battle Pass," which unlocks various rewards for your character — it costs 950 V-bucks ($9.50). 

To be clear, none of this stuff grants you stronger weapons or additional health or whatever else. The items in the shop are "cosmetic only and grant no competitive advantage." The "Battle Pass" carries similar language.

Beware, especially if young kids are playing, that in-game purchases start at $5. If you're worried about that being an issue, make sure to set up your parental controls accordingly.

It's hard not to recommend "Fortnite: Battle Royale." It's ridiculously fun to play, easy to learn, and surprisingly complex beneath the surface.

I've spent a ton of time spectating games after my own death, watching for strategies that I've missed. As it turns out, being able to break through walls and build complex structures from nothing turns the "Battle Royale" concept on its head. 

I was worried that "Fortnite: Battle Royale" was a shameless ripoff of "PUBG's" fresh new twist on shooters, and I'm glad to report that worry is unfounded. "Fortnite: Battle Royale" is yet another new wrinkle in the shooter genre, distinct and excellent unto itself.