Hugtopia checks off most of those requirements! It's a sci-fi game set in a city haven in a post-apocalyptic world with emphasis on character relationships + development, and it encourages characters to explore the plot at their leisure (with some events to push things along). The premise is that the locals all replaced their original bodies to become robots, but as it turns out, their world and gods needed its inhabitants' physical touch to sustain the environment. This is where the off-worlders come in to help, if they want!

It's easy AC (5 comments), a small game, DW, and friendly to LCWs. It probably would be an excellent fit for Zelda given her penchant for exploring new territories.