Liminal Horror is a modern cosmic horror ttrpg built on the Cairn engine.
And specifically, it feels like it's designed to emulate the tone and contents of a horror podcast. The scope is tight. Player characters come from all walks of life. And there isn't much expectation of institutional support---you're mostly alone against the darkness.
The PDF is 36 pages, with a solid, easy to read layout. There's a high density of public domain illustrations, and they're all consistent with the game's tone.
In terms of approachability, Liminal Horror feels like it's designed for people who already have a bit of experience with tabletop rpgs. The first non-credits section is a detailed, piece by piece explanation of the game's philosophy, and stats are introduced immediately after that. Basic rolls aren't explained until halfway through the book. There's no "what are dice" section.
That said, the game mechanics don't feel especially complicated.
Like Cairn, stats are simple, HP recovers fast, and there are abundant roll tables. You can put together a character in ten minutes, and most of that is nailing down the specifics of their backstory. In-game rolls are typically a d20 against a stat, with lower being better. Attacks always hit, but damage is variable.
Magic in Liminal Horror feels unique, as spells are one-shot effects that both take up inventory space and are randomly built from several roll tables. You can attempt to keep them after casting them, but this requires a stat roll, and the effects of a failure are somewhat debilitating.
Like a lot of other modern horror rpgs, Liminal has a mental Stress system. Stress, like damage, hits your HP track, then begins lowering stats. Unlike damage, you can get it from just seeing weird phenomena, and when it accumulates enough you gain Fallout. Fallout is a range of mental, physical, and supernatural consequences that permanently change you. Some entries feel similar to Call Of Cthulhu's Sanity/Mental Disorder system, but others are *very* much their own thing, and more than a few have benefits as well as drawbacks.
In terms of GM tools, in addition to the opening explanation of the game's philosophy, there's also a bestiary, a sample adventure, some roll tables for prompts, and advice on how to hack together new content. It's all short but thorough. There's even a compact rules reference and a character sheet at the back. It's a very complete package.
Overall, if you're looking for a modern supernatural game, you have at least a little bit of experience with ttrpgs, you want characters that transform (sometimes horrifically) during play, and you want a gloomy, isolated world-feel, Liminal Horror is a really good pick.