No, that's not a browser game. It is like 30-40 GB install (if I remember correctly) on your system which based on the assets and the amount of stuff the game has is very well optimized I would say. They have constant updates and new assets added to the game too. It looks good too with good smooth animations.
It is a bit grindy game, a lot of grind for, unlock a lot of stuff. But the gameplay never gets boring. The community is awesome too.
I see, sounds fun. Thanks for the clarification, bro.