This game is free on Steam. It looks like it once cost $19.99 but they changed to FTP (free to play) to attract new players. Many games are doing this now. The Steam website hasn’t yet totally changed to reflect the difference. At first I thought the $19.99 (now free) part was a dlc with better weapons, but that has a different price.
Many FTP games are just to introduce you to get you to buy things to stay competitive. That said, I’ve tried game giveaways from SoS (and FAILMID while it was here) and have enjoyed them, a few well past the FTP intro.
My advice is to check out the game on Steam’s Store page, or if you don’t have a Steam account Google for it, and either way be sure to check out YouTube to see the game in action.