Day 14: Which RPG do you prefer for open-ended campaign play?
That one is pretty easy. In the past 13 years my go-to-game for open-ended play has always been some sort of Vampire edition. Mostly Vampire: The Requiem or Vampire: The Dark Ages. But my tastes are changing again. Before 2004 I regularly gm'ed Dungeons & Dragons. Nowadays, Fate Accelerated Edition is turning into my go-to-game, as I am slowly moving away from dark gamers like Vampire.
Day 15: Which RPG do you enjoy adapting the most?
Easy one. Fate Accelerated Edition, closely followed by Fate Core. As a generic game, it usually needs some adaption to a specific setting in the way the aspect template is handled, some example stunts and maybe additional small rules additions to the robust core system.
Day 16: Which RPG do you enjoy using as it is?
Basically all that are not Fate Core, Fate Accelerated Edition or OSR. I like using games as they are written, and am very careful about introducing house-rules. One RPG stands out though. I had hacked Vampire: The Requiem 2.0 pretty heavily without first playing the rules as written. When I finally did, it turned out to be the most enjoyable Requiem experience I ever had. So, I do enjoy running VtR2 as it is.
Day 17: Which RPG have you owned the longest but not played?
At was at first tempted to say Mage: The Ascension . But I did play that and all attempts to do so crashed and burned. Besides, I didn't continuously own the first edition.
But the real candidates are my collector's items that I never bought for playing, but wanted to own anyway. So I am thinking back 1990s: By accident I found the original Space: 1889 books and the FASA Doctor Who game. But then I remembered my real catch from somewhere back in the 1980s. Either in the UK or back here in Germany: Red Box D&D Basic in a book edition. I think it was published by a UK company. And I've never ever played this, because I bought it as a curiosity. I've played plenty of other D&D edition, though: D&D Rules Cyclopedia, AD&D 2nd Edition (second game I ever played), D&D 3.0, some D&D 3.5, even one game of D&D 4th edition, and lots of D&D 5e. But never red box D&D Basic.
Day 18: Which RPG have you played the most in your life?
Disregarding different editions like Advanced, 2nd edition, revised, a pesky .5 or anniversary editions or different lines like World vs. Chronicles, the two games, I've played most in my life are Vampire and Dungeons & Dragons. Those are two games I've stayed with through numerous edition changes, change of publishers and shift of rules. I've been playing D&D since New Year's Day 1990, and Vampire since Fall 1996. I've had phases in my life where I didn't touch D&D and phases where I didn't touch Vampire. But both are my longtime companions and the lense through which I view gaming.
Day 19: Which RPG features the best writing?
For me that's Vampire: The Requiem 2nd Edition aka Blood & Smoke: The Strix Chronicles. The writing was crisp, inspiring and to the point. Transporting a lot of setting information in a less pages than 1st Edition. Also, reading was entertaining, informative and awakened a sense of wonder. I think it was written a lot better than 1st edition which felt like a chore reading through.