Death World woes

The thing about death world is that it is a completely different mindset compared to standard play. You need to be proactive about the attacks and push your borders before your pollution reaches the biters. Back when I did a playthrough I always cleared an unnecessary amount of space so the pollution cloud had room to expand. Also Military science is your #1 and #2 priority. You need to rush tank, defense capsules, damage and shooting speed upgrades, etc. Anything else comes after your military is well ahead. It got so extreme to me that basically I researched everything military related I could until the next science pack was needed, and only started to research the standard stuff when I couldn't advance military.

Also, world generation is key. The things that usually terrible make all the sense now. Lots of water features and cliffs? Yay, natural defense that biters can't overcome. Huge forest that makes it almost impossible to build? More like a free efficiency module that eats the smog.

I did a deathworld marathon game that spawned me in a desert with no natural chokes.

You can reach a point of no return. You must make sure you capture new resources before you run low.

Use efficency modules in miners. They are likely your most polluting thing other than boilers and furnaces.

Know your evolution level, and what level new stuff spawns at. You'll want to keep your pollution below those setpoints for a while. Make a big push just before Big, and then again just before Behemoths. That way you can secure new land, new resources, and maybe a new tech or two before things get too dangerous.

Flamethrowers make the rest of the game trivial, if still time consuming. Focus on securing oil early. I used crude to power my flamethrowers for the entire game.

Switch to electric furnaces asap, and put efficency modules in them. This will reduce their pollution to almost 0, and also remove the massively polluting furnaces.

Switch to nuclear asap. Nuclear reactors and steam turbines DO NOT generate pollution. Once you hit this point, biters will pretty much stop evolving, except when clearing nests.

Black science doesn't need oil.

Automate feeding ammo into turrets.

Stop researching anything except mil techs, then go claim more territory. You don't need to be researching something all the time. To make it stop flashing at you, just open, then close, the tech tree.

If they have evolved a fair bit you could be past the point of no return. But try some desperate turret creep towards the oil. Shut down ALL production except ammo/turrets/grenades and any cost effective damage upgrades. Attacks should slowly reduce a bit as the pollution stops expanding and you can focus more on pushing to the oil. I read, but haven't tried, that Defender bots don't need oil now - maybe that's worth looking into but sounds expensive :D

If it fails then maybe you need a reset. Rule #1 of deathworld: don't over produce in the beginning. Your only goal early game making a small compact base producing only the things (including research) needed to achieve oil and get the burnnnnnnnnnn going.

Rule #2 is clear the space you need to for your early-mid game (reaching oil, getting some red circuits running etc) fairly early when you can push quite effectively just with grenade spam and a couple of turrets for worms. Even if they recolonise that area, it will be much less dense than if ignored.

I find on death world (without some evil AI mod) you can do fine with just pillboxes of groups of turrets and some wall spam protecting them on strategic areas of the base, like corners / cliff chokepoints etc. I used to wall off entire base during bot phase but now I prefer using great wall approach and clearing out areas of the map once I reach Tank phase.

Then rest of production goes into turrets (manual turret creep is still pretty much the only way to take on bases with medium/large worms), grenades and regular ammo so I can punch a small hole to oil. AP ammo too expensive - use it only on your own weapon imo (till mid game). Its fine for your factories & furnaces to be in idle and only research important things to reduce pollution.

Maybe do a slow turret creep to those alien bases that are obstructing the nearest oil patch with those AP rounds after researching all the available bullet damage and bullet speed upgrades. If ore patches are about to deplete then first add new ore veins. Since there is no photo of your base, so I can't help much here. You need to figure out what's the immediate emergency and fix that be it oil or ores. If biters are in the way, turret creep them. If they turn out to be powerful than your weapons then first research the weapon damage and speed upgrades. Since you are only 4 hrs. into the game, biters probably wouldn't have upgraded themselves yet, depending upon your enemy settings though.

For reducing too much walking around the base, automate ammo production and refilling gun turrets. You need to do the repairs manually until you get the oil. You must cluster turrets with automated refilling around your base, clustering reduces the amount of damage enemies inflict on a single weapon.

Since you don't need oil for defender capsules. Make military science packs to unlock them. Research all the available weapon damage, speed and follower count upgrades first and then take them with you while turret creeping those alien pests.