The Gardener
That's exactly right!
and it's predecessor Afraid of Monsters are Goldsrc engine horror-shooters free on Steam and ModDB. These super underground Scariest Games You've Never Once Heard About In Your Whole Life Ever are critically acclaimed indie darlings, with millions of downloads and thousands upon thousands of positive reviews. And for good reason. They offer high-adrenaline and narratively thoughtful experiences which last several hours each. While some may find the horror rather cheap and the duology overly reliant on jumpscares (because they are), they are still excellent games and each well worth a playthrough. ... Just remember to 'Watch out for the TREES'.
It's actually in the list of the OP, but it's easy to miss due to its size. FreeDOOM is a 100% free and open source community project to make a new Doom game using the public source code of the original! Features two completely new campaigns, new art, music, weapons, a multiplayer mode, and more! Believe it or not, this is the first "DOOM" game I ever played and I will say- it's an excellent way to put your toe in the water.
