What game mechanics do you enjoy or that surprised you when playing a game? I recently started playing Tunic and I love building out the "manual" for the game and getting hints on how to play.
Mass Effect 1 is great for its time, good combats and good graphics. Also you could memorize the controls very fast, because it were intuitive and good distributed in the screen (also you had the help of the machine if you were too burned).
I love the Mass Effect series! (Only played the remaster) but I loved the way my choices had consequences throughout the trilogy. Like the dialogue trees were really fleshed out for their time, I'd even argue for modern day.