Factory lines, zippers & train economics

The factory line is the backbone of team game economics. When built correctly, a single train through allied cities obliterates what a port can earn. This lesson covers line construction, zipper technique, and the exact maths behind when trains beat ports.

Learning objectives:

• A factory auto-creates a train station for itself and for any cities/ports within 110 tiles
• Trains pay gold at every stop: factory to city 1 to city 2 to port equals 4 payouts per journey
• Gold per stop: self-owned station = 10k base, ally = 35k base, team/neutral = 25k base
• First 10 stops are full price; each stop after that loses 5k until floored at 5k
• Zipper technique: place cities as far vertically/horizontally from the line as possible while the line remains green to pack more cities into a small area and increase total income
• A zipper is superior to a straight line but requires coordination; randoms can break it
• 5 allied team cities on one line yields 125k gold per train, overtaking a max-tier port
• Full 9-stop line yields 245k gold per train: 9 x 25k = 225k plus 20k for stop 10
• For 2-3p lobbies: hard port spam is still optimal (simpler, fewer coordination needs)
• For 4+ lobbies: 2-3 early ports then pivot to factory line before hitting the 1M cost cap
• Global trade ship cap: as total ships across all players approaches ~400, spawn rate drops to near zero and ports lose value in large games
• Turn off trade with all enemies as every trade ship reaching an enemy port gives them gold too