Support for Negative Productivity

[Dweaver]

While 2.1 is adding miscellaneous final touches, I think it would be really nice if the engine supported buildings with a final productivity value of <0%, where, for example, a productivity of -10% means a building requires 10% more inputs per output produced; with a general implementation looking something like "if prod < 0, every successful craft adds [prod] to a counter, and if the counter >= 100, subtract 100 and cause the craft to fail".

IMO this would open up a lot of design space in mods for tradeoffs to other effects; for example, speed modules that produce more items-per-second, in exchange for those items being more expensive. Productivity modules are great for patching up bottlenecks caused by a shortage of inputs; so it'd be fun to have the option to "cash in" on a surplus.

Negative productivity as an effect already exists, but it feels pretty vestigial when it only matters when productivity is already being increased by something else. In practice, it only really counteracts productivity research, which is relatively niche, and also mainly relevant late-game where resource shortages aren't as common of an issue.

[Shemp]

I am amused by the idea of the productivity bar filling up backwards (i.e. from right to left).

For now, if you want to implement this sort of effect, you can restrict the recipe to a building that has base productivity, and balance that recipe's product amounts accordingly.