In Nil Quest you’re a colt living in a bleak future. Equestria has seen an explosion in technological growth and population. Ponies are augmenting themselves and pushing magitech to its limits. The cities are dense and crowded. The alicorns are gone and ponies ruined everything.  
Your mother cannot take care of you anymore, so you’ve decided to wander off into the City of Mareidian. It’s too expensive to get a even a cubical apartment, there is no work a colt can do, but in the abandoned industrial parks, underground tunnel systems, and urban wastelands exists plenty of spacious yet dangerous territory to settle into and find community. Just watch out for the magic pollution, disease, gangs, and monsters.  
It’s a post-apocalypse and not a single megaspell went off.
 
First Thread here: https://desuarchive.org/mlp/thread/34465687/