Ok. I'm going to share my own idea. I just wanted to see what other folks said before I shared the broader concept.

I've been recently interested in creating a crafting game with a greater realism factor. The idea is to be more realistic than most games where the player can just take sheet metal and a flint and make a lighter. That's way too easy. Then I realized how much the inputs explode in number with preliminary goods if everything is realistic. If every item is hard to make and each depend on a ton of other items, that are also hard to make, then the game would have a problem getting out of the bootstrap phase.

The idea to fix this it to have parallel recipes. Different recipes for different levels of a good. Crafting a level one of an item would be rudimentary. A single log of wood can become a crafting table with no extra steps. But making a level 15 crafting table would be more realistic. You are going to need a miter saw, screws, a drill press, clamps, a sander, and plywood or mdf.

Because multiple recipes would be supported it would not be hard to accept user submitted recipes since more than one can be correct. In fact that would be a more realistic way to source the data for some pretty expansive item trees. It would be easy for the user because it would be suggested just one item at a time, and there wouldn't really be wrong answers. Then we just have to rank which recipes are harder or easier to get the levels. Next the devs could easily tune the difficulty of each by adjusting the levels of input items needed. That's a lot of levers available to make it balanced.

Different levels recipes can also recycle a lot of the content from a lower level. The laziest and likely most standard way to create another level would be to add one or two more items to increase the realism and the also increment the input levels needed for a few of the inputs. But the structure doesn't glue the devs to that premise. It would also allow for primitive versions of things. For example beehives in real life existed before the modern variant. A level one could just be a woven beehive (basically basket making), and a level two could be a clay beehive. These are the two traditional primitive beehives. Beyond that you would be getting into the modern variant with wood stack frames. But levels within that can set if you need cinder block risers or if your frames need starter wax on them. The highest level might require cedar for the wood over pine.

So because this system can incorporate a lot of ideas and smaller crafting systems within itself I was curious if any of you have any interesting crafting game ideas. Either mechanics or things you'd like to be craftable in a game that you don't often see. The sky is the limit on how detailed something could get. A car could be made with sheet metal and raw rubber. Or it could be built in a system as detailed as a full game that is focused only on making cars.

Game mode ideas: I'm assuming a multiplayer system a bit like Rust.

One idea is to have a contest mode where players try to produce the highest level of a particular item. This would be a good way to get players to submit recipes just prior. Then the recipes could be recycled into the next contest.

The game could also have a battle royal mode where over simple recipes become unavailable over time. Then the challenge is who can survive the longest with increasingly high fidelity crafting systems.

Items that could be made: Beside the obvious everything, for me I'd be interested in making this pretty uncensored. I'd let people make nuclear bombs, dirty mines, chemical weapons.