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Activision is not just dipping its toes into the popular battle royale video game category. The Call of Duty publisher is jumping in, fully committed to take on current favorites "Fortnite" and "Apex Legends."

The new , "Call of Duty: Warzone," which launches today on Sony PlayStation 4, Microsoft Xbox One and PCs, "is the most ambitious environment we have ever built in the franchise's history," said Patrick Kelly, who co-heads Infinity Ward, the studio that developed the game with support from Raven Software. Activision on Monday announced the game, which lets console and PC players play together, with a post on its official Call of Duty blog.

Free to play online, and available to download starting at 11 a.m. ET/8 a.m. PT Tuesday, "Warzone" lets up to 150 players compete in a last-man standing combat game. Players who already have "Call of Duty: Modern Warfare," released in October 2019, get a , with other players getting access about four hours later (around 3 p.m. ET/noon PT).

"We brought a number of twists to battle royale," Kelly told U.S. TODAY. "I do think the world you play in is going to be undeniably unique. For one thing, we are initially going to roll out with 150 players, when you are typically seeing 60 to 100. Actually, I can tell you we are already playing with 200 players. We are going to release that a little bit later."

There's no secret to why Activision would want to join in the free-to-play battle royale competition. Free-to-play games accounted for four out of every five dollars spent in the $120 billion global digital games market in 2019, according to research firm SuperData, a Nielsen company. "Fortnite" alone accounted for $1.8 billion in 2019, SuperData estimates.

Free-to-play PC, console and mobile games are expected to increase about 2% this year to $88.7 billion, Superdata projects.

How do free-to-play games make money? Players can earn virtual money in the game, but most games also let you use real money to buy , which then you can use to get new items and features to customize and expand the game.

In "Warzone," those who have also played "Call of Duty: Modern Warfare" will be able to utilize their loadouts (specific weapons and abilities) from that game. But those who haven't played "Modern Warfare," Kelly said, can earn them, too. "Independent of whether you have ever bought the game (or) played the game, you can unlock and get access to that. So there is no paywall gating the functionality of the product," he said.

Infinity Ward began working on a "massive, open-world environment" several years ago, Kelly said. "We wanted that world to be as realistic and relatable as possible, so we modeled it after real cities and real locations around the world," he said. "We wanted each one of the buildings, for example, to feel real like something you would see in the world."

Where other games may have 100 to 200 buildings, "Warzone" has "thousands and they are all very real," he said. "There's an , there's a , there's a downtown section, there's farmland, suburbs, you name it."

The studio is developing new features for the game even as it launches. Initially you can play solo or as a duo or trio. "So let's say you show up alone and just want to play solo ... or if you show up with a buddy you just check the box that says, "Don't fill my squad' and you will just be a duo," Kelly said. "I can tell you we have 4- and 5-player squads we are already playing with. But we want to launch with something we know works really well and we have tested to the nines and then play around with these different team sizes."

"Warzone" launches with two modes: Battle Royale and Plunder. Some of the twists that "Warzone" brings include "kill streaks," which are found in Call of Duty games, missions that earn virtual currency—and you can use that in-game currency to buy a fallen teammate back into the game.

When you inevitably get knocked out of the game, you can be sent to the Gulag, where you compete in a head-to-head gunfight to return to the main game. "We drop you into (the Gulag) and you've got a pistol or a shotgun and you are chasing (your enemy) around and you have a fight, obviously to the death, and one of you respawns," Kelly said.

In the Plunder mode, players "gather as much money as you can," he said. You can find money throughout the world, but you can also complete missions to earn it. And, if you prefer the mercenary strategy, you can kill off other players to take their money.

This game mode has a respawning twist, too. "When you die, you do drop half of your money at your point of being downed, the place where you got killed. If no one takes it, you can go pick it up again when you respawn in," Kelly said.

Players can also deposit their money during the game, by securing it at certain helicopter pads. "But, of course, when you do that, everyone in the world, especially nearby, can see and know somebody is calling to deposit a bunch of cash, so it can be a high-risk endeavor," Kelly said.

Infinity Ward's game designers are working on other modes, too. "We want this to be continuously emerging and we want it to be something that really continuously surprises and delights players," he said.