This is something that's been bouncing around in my head for a while. I've always loved "mons" stories and games- Pokemon, Digimon, Monster Rancher, and more recently the Monster Pulse webcomic. That said, oftentimes the aspects of these stories that intrigue me the most aren't the main focus of the work, but questions about the worldbuilding, and in particular the way society has built itself up with such a close relationship to poorly-understood supernatural beasts that they at times take the place of conventional technologies and infrastructure, whether that's a city where power is provided by fire-breathing behemoths or a world where sentient monsters personify all digital programs.

Well, it just so happens that my favorite RPG system can easily incorporate that into its themes and mechanics without actually changing any of its rules. Legacy: Life Among the Ruins is a game where each player controls both a faction (anything from a state to an industry to a faith group) and a series of individual characters across multiple generations, beginning as small groups of survivors after a great cataclysm. The tagline is "Building a new world in the ruins of the future."

One of the central conceits is that this world (which the players have a great deal of agency in helping to establish and build, even as the GM's role is to fill in details and bring together the parts put forth by the players into a coherent whole) is littered with "devices," pieces of tech that can seem borderline supernatural. They're one of the primary resources factions compete and collaborate for throughout the game, and the rules are designed to keep them always in a somewhat mysterious state, where their nature and purpose are hinted at but never completely established until actually triggered or investigated in the fiction.

Adding in the conceit that most of these "devices" take the form of seemingly magical creatures, whose nature and origin is a mystery that the players can contribute to both solving and muddying, doesn't actually change anything about how the game works and plays.

With that said, I suspect this idea might be a bit too niche. Does what I've described sound intriguing to people? I want to see if perhaps the idea of a 'mons-style rpg with a focus on collaborative worldbuilding is something people are into, but if I've lost them with references to a generational indie rpg, even if it is newbie-friendly. Or, conversely, if perhaps there are quite a few people on this board who'd be interested in a game of Legacy: Life Among the Ruins, but without adding in the 'mons elements.

I actually like this idea a lot. Legacy is one of the games I've wanted to run but haven't had time at the table for.

It might be a bit to niche as you say, but I wouldn't let that discourage you. I'd bet you'll find more than enough curiosity to fuel this game.

I'm in for any Legacy game, I've been itching to try it ever since discovering it through a spin-off (Voidheart Symphony, a Persona themed take on Rhapsody of Blood, a castlevania themed take on Legacy). I haven't had a chance to yet, though, and this theme is right up my alley! I'll definitely submit an RTJ if you decide to do this.