Hey guys this is off topic but I'm extremely confused as why it costs  $20 on steam but its free here.  Are there any missing features or something? 

this one is the prototype version. it doesn't have multiplayer, and may be missing a lot of content as the creators probably dropped it after they made it onto steam as a paid game. plus the graphics compared to the steam one are pretty bad, just compare the ones from the steam game page to this game page and you'll see the difference. i'm broke though so i'm gonna get this one. i'll let you know if a lot of stuff is missing once i play it.

Yeah, this version doesn't have much in it. If you're new to the game and haven't watched anyone play, you'll die a few times until you figure out how to purify water and eat, as it doesn't have a help/tutorial, or a reasonably polished user interface. Once you figure out how to drink and eat, it's up to you how fast you can do everything available in the game. You might be able to finish it in an hour or 2-3, depending on your skills and maybe even PC performance. :P

There's not a lot of content compared to the game on Steam, and it looks a bit rough, but it's still a fun game for a couple of hours. :)