Played with it for a while, and each seed I've generated ends up requiring >1k raw resources to build one of the initial products. Love the idea of this, but it's completely unplayable without some kind of check like this.
Eg. Steam engine requires 40 iron and 40 gears, ok that's not crazy unreasonable... but each iron requires 3 copper, and each copper requires 5 stone ore. And each gear requires 5 stone ore. So it's going to take 800 stone ore to get an engine. Well, that seems excessive.
Maybe there just needs to be a restriction vs. how many raw resources would go into the equivalent product in the vanilla game. If a steam engine normally takes ~100 raw resources to build, the random recipe should be +-20% of that, and so look at removing the high multipliers for the recipe. In the above example, it would suddenly be very reasonable if it only took 10 plates and 10 gears to make it. This +-% can be a parameter setting as well, although with a minimum range to alleviate compounding problems (although you could also just say it's a restriction unless 1 of each intake exceeds the threshold, and then still allow the recipe - if the source product recipes are subject to the same constraint then it shouldn't ever get too bad).
If calculating all of this is overly complex, there should probably also just be a limit as to how nested the recipes can get - if I need stone to make iron to make copper to make a steam engine to make an inserter, it's too complicated :)
