I had plans to do such a thing; plenty actually where I could introduce a crafting system, basic top-down hack and slash combat and dungeon's with puzzles + write up a document for people to make their own to be found in the middle of a wasteland, even going so far as letting those dungeon's be treated as cities for kick's.... But there are, somewhat, other's that accomplish this or are already and finding help for dungeon design, music and artwork is difficult, especially when one's talents are programming and the only use folks have are WANTING TO PLAY TEST WHEN IT'S-A-DONE!.. I gripe and complain to which I apologize, that was a while ago in terms of years before one give's up and needs to work on smaller scale things. As a fella who hunt's obscure game's, I've come across my odd share of them; though be mindful that the one's I found have some extent.
The more obvious one is 'The Survivalists' by Team 17; you play as a shipwrecked survivor in a 2D world where you need to build a home, explore, gather stuff to eat and craft a home for yourself. There's a main quest-line to escape the island of massive ocean of islands and you gather/recruit Monkey's to help your current situation as you assign one set of them to act as guard, another set to build, harvest, gather, transport goods and so on. More monkey's you have in your army/village and the more well trained they are in certain skills, more powerful you are as a player; so much so that when you visit other plyer's, you bring a small group of your best monkey's with you to escape together.
8 Bit-MMO is another example, though done in an MMORPG setting. The only difference is that it's a world built by the player's. You can travel to the end of everything in a world, build a dungeon and leave it for other player's to find or find something someone else made. It meet's the criterea, but not that well.
Rogue Heroes and the Ruins of Tasos I think fit's this a lot better as it's 2D, it's an open world and has hack-n-slash mechanic's similar to the Legend of Zelda. You find stuff, use that worthless stuff to make bigger stuff and bring that bigger stuff with you into ruins and dungeons to seek your fortune. You can go alone or with friends. I plan to write a post about it when the criteria meets the timeline of it's age.
