Being relatively new to the world of IF, I have been working my way through the XYZZY 2018 Award winners. I figured starting with a "best of the best" list was probably a good way to give the genre the best possible opportunity. So far, I.A.G. Alpha has been my favorite.
I.A.G. Alpha was a hoot to play, from start to finish, and kept me guessing right up until the end. It was on the lighter side in terms of "wordiness" and, with getting tripped up by a puzzle or two at the end, only took about 2 hours to play through.
The writing is good, where it exists, but like the author points out in the description, the game is unfinished... wink, wink. The puzzles range from pretty easy to moderately challenging. One non-spoiler hint I'll leave you with: utilize the save functionality, particularly as you progress into the latter part of the game.