That's an inherent part of slot based inventory. No way to really go around it.
Transition from slot-based inventory to weight-based one would be a rather major change.
Might be worth considering, though.

You can always slow down to reduce the pollution. That's how I handled "hard mode". My hard mode might have been a bit easier than yours (I think I had bases big and frequency high), but same tactics apply. Full efficiency + solar panels + electric furnaces would mean that most - if not al...

Would also like it if there were issues like radiation leaks, possibility of explosion, damage to surrounding area if it does. Maybe leaks could be just a super low random chance and they could be repaired. Explosions could come from being damaged to the point of breaking I guess. Strong against he...

+1 for removal.

The literally only good thing pickaxe adds to the game is the small buff when you upgrade from iron to steel.

Smell based simulations tend to be either computationally heavy or imprecise. While this would fit with the concept of pollution and could easily use existing mechanisms, weaker computers could have problems passing all those pheromones around. I really like the idea of death pheromone. Could be use...

Fun fact: this suggestion has 3 threads about it on 2 first pages of "Ideas and Suggestions".
I think we need a "Do not suggest those, bump the existing thread instead" sticky with links to the reoccurring suggestions.

Lighting gun: I though about that exact real life example for why your idea of lighting gun is unrealistic. It would ground itself out on first target. Also, I've yet to see forking lightning done well in games. So far it was always just "fireball but blue and fast". About realism: have yo...

I don't like the grouping of types. You get clear progression within a type, which is a bad thing as it limits choice. As weapon types are associated with damage types, balanced biter hordes would mandate having reasonably developed weapons from all tiers, once again limiting choice Progression in e...

Diesel internal combustion engine would be amazing for early game and small stations far from water.

If biters aggressively predicted target's movement, they'd run in front of the train, clogging it with their bodies. First small biters would slow it down, then mediums would pin it, 2 big ones in front of the train could easily wreck a locomotive. That would make train guns helpful, without needing...

So... a different type of accumulator? There might be an argument to be made for that, or the ability to 'tech up' existing ones with rarer materials or larger footprints Too boring. Accumulators are already very boring (plop and forget), but at the same time fulfill their purpose. Better accumulat...

In Factorio, you can produce energy from hot water all day, but from sun only when the sun is shining. With an electric boiler, you could heat up water in the day when you've got excess power and then use it up in the night. You can already store hot water from regular boilers to decrease fuel usage...

Electric boiler could be factorio's imitation of another real life concept: pumped-storage hydroelectricity. Since storing energy chemically (in accumulators) is expensive, it is more economically viable to pump water up a river when there's excess energy available and run it down through a turbine ...

It makes sense to have large, low-density "farms" supply dense "city". It is both realistic and simple to implement. It becomes rather boring later on, though. Solar panels are very simple and thus uninteresting. It would be more interesting if it was done like it is in real life...

Clever pathfinding could allow biters to avoid heavy turreted and walled areas while being very easy to implement.

Why would a solar boiler be expensive? Like regular boiler, it requires entire clunky infrastructure around it. The infrastructure is a cost in itself, so it should be more resource efficient than solar panels. Most efficient solar power plants IRL are essentially solar boilers, except they use a wo...

It could be cool for the advanced belts. Basic ones should be upkeep free, though. Early on, belts are the only transportation you have (other than "manual inserter") and they have to cross relatively large distances. Until we get low-tech steam trains that don't require steel and lots of ...

Solid fuel is - as name suggests - solid.
You put oil to chemical plant via pipe, but then inserter takes the solid fuel out of it (like from assembly machine). You can output those cubes onto your coal belt and furnaces will accept them as soon as they burn all coal stored in them.

+1
Being able to be filled to the brim is an essential feature of storage chests. Having free storage space is essential for valid functioning of deconstruction.

At the moment biters "evolve" with pollution, but it's very linear (small->medium->big). I can kinda see an application of genetic algorithm styled evolution here. Biters could have a separate difficulty and stat distribution attributes. Difficulty would determine sum of stats and increase...