Hear that sound? No, you probably can't – at least not the sound I'm referring to, which is the free game klaxon. It sounds every time I notice a PC game has been offered up for free, and frankly, I hate the damn klaxon.
But what it signals is nice enough. This time it's heralding the free-ness of Shadow Warrior Classic. It's the old 1990s Shadow Warrior, so you'll need to have some patience for the way FPS games used to be, but even if you've no intention to play it at least it's damn free.
That offer linked to above is on GOG, which bundles in all applicable add-ons and expansions. But it's also free on Steam, though without the aforementioned bonuses. Go forth and slay – it's a worthwhile curio, especially if you're a fan of the rebooted Shadow Warrior series.