is roger federer still playing tennis?

Yes.  Roger Federer is still playing tennis. He is one of the best tennis player. 

You don't PLAY tennis, you LIVE tennis

Yes. Roger Federer still playing tennis. He is all time star player.

Yes of course, you will see him in his next 

He might be getting ready to do his final tour.

Due to knee injury the tennis superstar Roger Federer will be out until the start of the 2021 season. He is planning to take the necessary time to be 100% ready to play his highest level. He is now 38.

He's out for the rest of the year due to knee surgery. But don't write him off completely just yet. Remember in 2016 he didn't play for the whole rest of the year due to a knee injury after Wimbledon and came back 7 months later and in his first official tournament back won the 2017 Australian Open,  then won Wimbledon at 35 without losing a set later that year. And don't forget he very nearly won Wimbledon again last year, had 2 championship points for God's sake. So I don't think he's finished just yet. The only thing missing from his CV is an Olympic gold medal in singles so maybe that's spurring him on a bit. 

I hope we'll see him back BUT equally I hope he doesn't come back and fails.

Yes he is.  Although, it does say he is not going to play again until 2021.

Roger Federer has confirmed that he won't be retiring before 2021 as he has committed himself to participating in the next year's Tokyo Olympics. Roger Federer addressed speculations about his retirement after he confirmed last month that he will be out of action for the remainder of the year due to knee surgery.