http://store.steampowered.com/about/

Steam is a software developed by valve (the people who made half life, counterstrike etc.) and its a platform where people can release their games, for good prizes and in a proper enviorment so everything is safe and trustworthy.
even bigger publishers use steam to distribute their games and so does toribash to hit a wider base of players, because, lets be real, who goes through the internet and to search for a certain game hours upon hours to find something?
on steam you have nice and quick filters to find games of your liking. toribash uses that to their advantage to reach more players.

steam is free.
toribash on steam is free.