(I played the commercial version of this game.)
The Roottrees Are Dead is what you might call an Obra Dinn-like, a subgenre of mystery game in which you're given certain information about past events involving a large group of individuals and must organize that information and use it to find more, with identifying which person is which a major aspect of the gameplay. The commercial version consists of the base game, which I understand to be the same as the free version except for having new art, and the new "Roottreemania" scenario.
Other entries in this genre that I've played have mostly revolved around gory deaths and supernatural happenings, but Roottrees has lower stakes. Here you're doing genealogical research to untangle the family tree of a wealthy family, and the game is quite adamant that there are no skeletons in the family closet worse than infidelity and a bit of period-typical homophobia (anytime there's the suggestion that something more dire might have occurred, you quickly run into assurances that that's not so and is just conspiracy-theory sensationalism). This may disappoint fans of the genre who prefer the darker vibes of Obra Dinn itself, Type Help, or the Golden Idol games; on the other hand, there must be people out there who enjoy the style of gameplay but would prefer to do without all the murder and curses and whatnot, in which case Roottrees might be exactly what they're looking for.
The base game seems very well designed, with reasonably logical connections between bits of information, a decent amount of redundancy (I missed several documents referenced in the wrap-up but still managed to fill out the family tree, including almost all optional info), and a story that can get a little melodramatic in parts but never seriously strains credulity. I found it a bit on the easy side, but I've played a lot of this type of game and done a lot of logic puzzles (plus I used to have a job that involved fact-checking via information publicly available on the internet, which might have helped).
I did come out of it wishing for a bit more challenge, but "Roottreemania" soon had me feeling like I'd made that wish on the monkey's paw. "Roottreemania" does several things to increase the difficulty, but in general I found them more frustrating than fun:
There is more information that can be found in only one place, without even nudges in the right direction when you search something that's close-but-not-quite, leading to more bottlenecks.
In particular, there is a lot more information that can be found only in periodicals and not from the general in-game web search. There are also more periodicals and there is less hinting towards which ones would be useful to search on a given topic. This leads to a certain amount of busywork plugging search terms into every available periodical.
Texts are, on average, longer, leading to a certain "pixel hunt" feeling of "wait, which proper nouns from this very, very long article have I not searched in every available database yet?"
There are more multi-step chains where you have to go down a rabbit hole that at first glance doesn't seem relevant in order to get necessary information, but the game will also let you go down rabbit holes for red herrings sometimes, meaning that just the fact that you're still getting information doesn't mean you're on the right track. A more authentic internet research experience, perhaps, but not ideal for a game.
I ended up making a lot of use of hints while playing "Roottreemania", but the adaptive hints respond to what documents you've seen and not to what bits of the family tree you've locked in, and as there is still some redundancy, that wasn't always the most helpful.
Parts of the narrative in "Roottreemania" felt a bit more contrived as well, with some obvious retcons.
I did enjoy my time with the game overall; the gameplay in the base game is satisfying even if it is a little easy, and the writing is often fun--it is at its best when poking gentle fun at internet culture and the ways people interact with celebrity. (This is set in the '90s, so the oversharing, parasociality, and general weirdness aren't quite in full swing, but the roots are visible.) But I didn't feel that it ever quite managed to offer a difficult but rewarding challenge.