I had a very successful first game of Mechwarrior: Destiny.
I run a regular D&D game at a youth shelter in my city. We're between campaigns right now so have been trying one-shots of other systems. I was planning on running ATOW, but the beta rules for MW:D came out just in time, and since it's a low-prep game, I read the rules and got a session ready within a few extra hours on the weekend.
The shared narrative was a huge hit with the shelter youth. One of the things I'm always trying to do with the youth is to create situations where they are empowered to affect their world. In D&D with the traditional delineation between game master as God, physics, and NPCs, and players as just their characters I spend a lot of time working with the backstories and perceived desires of the players to produce content where they feel they have meaningful choices and are part of the world.
The system of Mechwarrior: Destiny did a pile of that work for me, and to a better result than I've had with this group in D&D.
All the players found the pregenerated characters to have ample flavour to hook into. A player I have who always roles up different classes and races, but always ends up creating the same high-status holier-than-thou character, actually departed from their habits and got inside the head of Lovasina.
I ran the "Use the Diversion" briefing with some extra lore about the players being connected to locals on a planet that has changed hands and the new FedSuns duke is bringing in settlers to strip mine, chasing the locals out of the cities. The players are part of the rebellion and need to raid a fort to get a copy of the surrender agreement which they've been told guarantees them rights that are currently being trampled.
They bought in right away. Without having ever played anything "battletech" were able to get the flavour just from the character sheets. They invented a whole new scene right off the hop of going to a strip mine and trying to steal a mining mech to infiltrate the fort in. They failed miserably, but one of the players introduced with a plot point that the MP Officer who was taking them into custody was her Ex and still had feelings for her. Out of the player's imagination was born Captain John Michaels, strictly disciplined security chief, but with such a soft spot for Jaimie that he believed that she was indeed forced into trying to steal a workmech by evil rebels and who's feeling allowed the players the chance they needed to escape the Paddy Wagon Hover Craft and start a firefight in the base courtyard.
With the extra scene, we didn't get to the end of the briefing but finished on a great cliffhanger of another character's girlfriend storming through the fortress gates just as John Michaels orders them opened to let his ex-wife and her two orphan dependents leave to avoid the battle.
The response from the players after the game was adamant that they want another session and they've asked if we can play MW:D instead of D&D for the next big campaign.
I loved it because as a game master I got to welcome player's ideas about the world and I saw the adventure become personal and enticing to the players without having to guess what they wanted from the experience.
I'm a big fan of the system so far.