First of all, my sincere condolences.
I've played several titles from this list. They're mostly dark-themed titles, but I also see several "lighter" ones. I'll try to write a few words about the ones I've played.
Mata Hari
Nice graphic and music, but rather boring and uninspiring story and gameplay.
Return to Mysterious Island
Eye-candy graphic, charming world and characters, engaging puzzles. The sequel is IMO equally good.
Barrow Hill
I haven't played many horror adventures so far, but Barrow Hill is certainly one of the finest I've played. My personal preference in this genre are games by Johnatan Boakes. I would definitely recommend all of them if you like Barrow Hill.
NiBiRu
Atmosphere and locations are strong point of this game. The story is also rather intriguing. The similar games, at least when it comes to atmosphere, is Black Mirror triology.
Art of Murder
These are high-production titles for sure, but the characters, story and gameplay is full of cliches.
Agatha Christie triology
Personally, I didn't read much of Christie's books so far, so I'm not entirely sure about the accuracy of these games when it comes to story. To me, all three were interesting and captivating. Overall, these are good-looking and well-polished-up titles.
Secret Files: Tunguska
Despite it's high quality in technical sense, this title IMO is rather cheesy when it comes to story and gameplay. The voice-acting is also a red flag. Still, both Secret Files games means plain good fun. There is also the third game on the way, and if you like them I would also recommend The Lost Horizon.
Paradise
If you've played other Benoit Sokal games, namely Syberia, you would likely be intrigued by the screenshots of this game, because it also has his trademark design. Personally, I didn't even finished this game yet; I've found it boring and tiresome.
Ceville
Fun and colorful game, in the style of newer Monkey Island titles, though nowhere of the same quality. If you like this style of games, I would also recommend The Vampyre Story.
Portal
Though certainly not a typical adventure game, Portal is one of the biggest (pleasent) suprises I came across. The sequel is a must, and even much better then the original game. It is IMO pointless to describe this game, you simply have to experience it yourself.
