Don't worry, You don't need to make a new account.
okay thanks for your helpful information
Yes. don't need a new account.
dont worry about it.
You don't need to make a new steam account. I had the same Q, so I contacted support and got this reply:
Hi! You can play it with your actual Steam account, the point is to register in game by our Play for free link. Good luck! :)
well thank you @fluff2 you confirmed it to me i shall start then doing the task :D
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!
Do i need to make a new steam account so i can finish the task for the games like Heavy Metal Machines ? or i can stick to my old account as my account is nearly 8 years ,but i didn't play Heavy Metal Machines once....... if you got any idea on what to do drop a comment to help :D