If you want to do game task through your phone, its better to download Gamehag from Play Store. After you download it, then you can play games from the task listed.
Thanks
You are welcome 
in 3 steps
Choose the game that interests you and play itfor free.
Every game has some quests for which you will receive Soul Gems.
You can exchange your Soul Gems for Steam Wallet top-ups, game keys, CS:GO Skins and other rewards.
You know that on Gamehag you can get real rewards for free, right? Join us, complete walkthrough and get your chest!
How to play the games offered in phone or computer. Is it possible to play in my phone