Of the seven essential accessories for the train upgrade, he had already built the "Generator" and "Electrical System." They just weren't in use yet, since he didn't have a spare Energy Stone. He'd tried to pry the one out of Boss Kun's old engine, but it was clearly not a removable part. He didn't dare smash it with a pickaxe either—if the stone exploded, he'd be done for.

That left five essential accessories he still needed to build: the "Pure Water Filter," "Windfire Wheels," "Carriage Steel Armor," "Pickaxe Head Production Line," and "Axe Head Production Line."

He had to get the train to Level 2 as soon as possible, or he risked getting stranded in the middle of nowhere. He wasn't short on pure water for now, the armor was too expensive, and he had plenty of scavenged pickaxes. The best choice was to build the Windfire Wheels to increase the train's speed.

When scavenging an enemy train, some accessories like the "Tripod-Mounted Heavy Machine Gun" could be uninstalled. But many others, like armor and wheels, were integrated and couldn't be removed.

Wait—

A thought struck Chen Mang. He didn't need more pickaxes right now, but what if upgrading the "Pickaxe Head Production Line" made the pickaxes mine faster?

He quickly returned to the cockpit, pulled up the "Novice Guide" on the control panel, and scrolled for a while before finally finding the information he was looking for tucked away in a corner of the screen.

[Pickaxe Head Production Line], Green Grade, maximum level of 3. Each upgrade allows the pickaxes it produces to excavate higher-level mines.

That's it? It only lets you mine higher-level ores?

Chen Mang frowned at the text. It wasn't useless—at least it meant that in the future, he'd be the only one who could easily mine Level 4 and higher ores. Even if others managed to get a Level 4 pickaxe, it probably wouldn't be as easy for them as it would be for him.

Still, it wasn't quite what he'd been hoping for. A bit disappointing. He wondered if Level 4 iron ore could be used in place of Level 1.

Soon enough, he found the answer he was looking for in the Novice Guide.

10 units of Level 1 Iron Ore = 1 unit of Level 2 Iron Ore. 

10 units of Level 2 Iron Ore = 1 unit of Level 3 Iron Ore. 

10 units of Level 3 Iron Ore = 1 unit of Level 4 Iron Ore. 

On a "Crafting Station," 10 units of Level 1 Iron Ore can be combined into 1 unit of Level 2 Iron Ore, or 1 unit of Level 2 Iron Ore can be broken down into 10 units of Level 1 Iron Ore.

Perfect!

A satisfied grin spread across Chen Mang's face. This meant that as long as he found a Level 4 mine and upgraded his "Pickaxe Head Production Line" to Level 4, every unit of Level 4 iron ore he mined would be equivalent to 1,000 units of Level 1 iron ore.

Suddenly, the problem was much simpler. He just needed to find a Level 4 iron mine to solve his current resource shortage.

Finding mines required two things: the "Train Radio" to ask other captains, and the "Resource Detection Radar" to scan for nearby resource zones while moving. Both of these were default craftable accessories that unlocked when the train reached Level 2.

In other words—as long as he got his train to Level 2, all of his current problems would basically solve themselves.

By breaking down the problem and clarifying the logic, he had a clear optimal path. The goal was now specific, saving him from running around like a headless chicken, feeling like he was short on everything and not knowing where to start.

Having sorted out his priorities, he looked at the five remaining essential accessories and chose three.

"Pure Water Filter," "Windfire Wheels," and "Pickaxe Head Production Line."

He placed the filter in Carriage #3, the living quarters, and the production line in Carriage #2, the warehouse. The current layout wasn't perfect, but without the resources to build more carriages, he'd have to make do. He could always reorganize later when he had more ore.

The three accessories cost him a total of 700 units of iron ore. He was completely broke, without a single unit left to his name. Producing a single pickaxe head from the new production line would cost 10 units of iron ore.

The "Pure Water Filter" could turn any liquid—urine, rainwater, you name it—into drinkable pure water. It looked disgustingly like a toilet. Upgrading it to Level 2 would allow it to produce mineral water directly, with each bottle costing one slice of moldy bread.

Meanwhile, the Windfire Wheels had already automatically replaced his old, standard wheels. They gave the train a significant speed boost, but the downside was obvious: they were practically useless against a zombie horde or on rough terrain, with a high risk of flipping the train.

And so—

He was now only two essential accessories away from upgrading his train: "Carriage Steel Armor" and "Axe Head Production Line."

The "Carriage Steel Armor" was the most expensive of the lot, costing a steep 1,000 units of iron ore. Worse, that was the price per carriage. To armor the entire train, he'd need a fortune. Luckily, he only needed to armor a single carriage to meet the upgrade requirement.

No wonder Boss Kun's old train only had armor on the engine.

"This is so stressful," Chen Mang sighed inside the cockpit, glancing out the window at the mine entrance. The slaves—passengers, he corrected himself—were still inside mining. It would be a while before they came out. He was almost tempted to grab a pickaxe and start digging himself.

He needed more slaves!

Oh, right. He had to get used to the new terms. More passengers and survivors, as Lao Zhu had put it.

There was never enough iron ore.

It was a shame he wasn't qualified to build the "Train Radio" yet. Otherwise, he'd love to know how other train captains dealt with resource shortages. The lack of information exchange was a real problem.

But then he remembered something.

Could his "Geocentric Furnace" melt down the scavenged handguns and bullets?

He decided to find out immediately.

He walked out of the cockpit, activated the "Geocentric Furnace," and as its great, bloody maw opened, he tossed in a handgun. A moment later, he had gained 10 units of iron ore.

"Hmm."

Chen Mang pursed his lips. It wasn't much, but every little bit helped. He then threw in all the scavenged handguns and the 200-plus bullets, netting him a total of 250 units of iron ore.

He held onto the "GLS Handgun" he'd received first, along with about thirty bullets. Even though he had assault rifles now and didn't really need it, it was the first lifeline he'd had in this world. It was worth keeping as a memento.

He had to build a secure train of his own, and fast. If he ran into another zombie horde that had already formed an encirclement, he'd probably have to abandon all his carriages and flee, just like Boss Kun.

But if the train were strong enough, who the hell would run!

He'd slaughter them all. Maybe he'd even get some good drops!