No surprise, free-to-play games are the kings of getting people to download. As far as the stats show, PUBG is the top downloaded game with 1 billion players worldwide.
Some other top contenders include:
Crossfire- 1 billion users
Dungeon Fighter Online- 700 million users
Speed Drifters- 700 million users
Minecraft- 600 million users
Candy Crush Saga- 500 million users
Among Us- 500 million users
Microsoft Solitaire- 500 million users
Fortnite- 350 million users
Now, these numbers do get a little complex sometimes. After all, some companies only publicly track open accounts, others share peak amounts of users each month, etc. The complicated part is that since so many of these games are free to play, there are a decent amount of players with multiple accounts for different reasons, so just tracking the number of accounts isn't always accurate.
For example, notable top games like League of Legends (111 million monthly), WoW (100 million), Overwatch (50 million), CS:GO (46 million), TFT (33 million), and DOTA 2 (13 million) are not in the top technically, even if they still rake in millions of players. Video gamers love those titles, and the general expectations are to have even more people playing video games in the years to come.