The game boy color aesthetic lured me in, and the exploring-by-solving-puzzles loop kept me hooked. Akurra is fantastic - I had to play all the way through the demo on one sitting. There was just enough loose ends available at all times so that if I got stuck in one puzzle, I could just go look around for other mysteries to solve (and there seemed to be a plenty of them!).
When the end screen finally showed up, i audibly gasped - OH NO it ended already!! And that, if something, is the best feeling a demo can give.
...And to be fair, the demo was also much longer than I initially expected, and there was just the right amount of puzzles left after the play-through that I gotta return and 100% it. (my completion time and rate: 1h 33m, 75%)
This will be a day one purchase for me.