Well, dude there are a lot of gaming tournament platforms, however it actually depends on the game you are interested in. Per example you can take toornament com, the most popular games on this platform are PUBG Mobile, Fortnite, Fifa 20, Counter-Strike: Go, League of Legends, PES 2020, Overwatch, Apex Legends. There is also World Gaming, and the games are basically the same. So you just need to find the one that fits the game you want to play. As you said the most platforms are interested in games like cs:go, because of its popularity on the esports arena. This game got that popular especially due to the introduction of skins, and legendary trades like m4a4 howl back in 2014, it was sold for more tha 100K. I mean, that is clear why this game is so popular in this domain.