Left Behind is in close contestation for the title of my favorite episode!
Storm Reid's performance as Riley was the highlight of the episode overall for me! I always thought Riley was a cool kid, but Reid brings juuuuust the right dosage of additional liveliness to the character for my taste. Not an ounce too much or too little.
Some of the top moments for me included:
-Seeing the awe in Ellie's eyes as the mall lights up. The sense of childlike wonder here was palpable and highly endearing.
-The girls getting to actually play Mortal Kombat II, complete with fatalities. That was awesome. 
Honestly, there will always be a special place in my heart for the game's more nuanced version of that scene, but I'm so glad that this alternate version exists too because it was so much fun to watch just as a lifelong gamer who does in fact happen to have some treasured memories of my own playing MK2 at the arcade. 
-Bella Ramsey's outpouring of rage near the end of the episode where she shatters every glass surface in sight was a sight to behold and a promise to us that she will be up to the task of delivering us Part 2's rage-filled version of Ellie in the future.
I also just really liked how this version of events more directly connects Ellie's past relationship to Riley on the one hand to her current one toward Joel on the other. Joel and Ellie are both spurred on by past losses to keep from losing each other and in that crucial way are very similar people.
Ultimately, Left Behind, in both the game and this adaptation, is about appreciating the smaller things in life that we so often take for granted. This version was at least as successful as the game's to me at conveying that.
