If you are a gamer that wants to know you'll be able to pick up the Big New Thing on Linux... we aren't there yet. That day may come soon-ish, but we aren't.
But if you are someone who is primarily interested in--or at least sufficiently satisfied by--the wide indie game market, Linux has been there for a little while now. Hungry indie game studios generally build with tools that make building for Linux easy, don't build games that hit driver edge cases, and they are hungry for the money the smaller Linux market provides.
I know one minimally technical gamer who uses Linux exclusively for work and games. He's very satisfied by the indie game market. He's an exception... but he's a sign of times to come.