I see so many games, are these all free games?

It asked me to download a game, but I don't want to download it. Can I play games without downloading?

I game frequently. Is there a leaderboard to track my progress?

Can I play online games by inviting friends?

I am looking for a specific category of game. How do I discover it?

I play games very frequently and have won some rewards. How do I claim them?