City number four. Same rules: GHSL 2025 population (18.3 million people in a 41 × 44 km box), 19 food hotspots, 6 independent growths of 50,000 agents, and we count the people living within 800 m of a line. The real network is every Kolkata Metro line open on 25 Oct 2026: Blue (Dakshineswar to Kavi Subhash), Green (Howrah Maidan to Sector V, including India's first tunnel under a river), Purple (Joka to Majerhat), Orange (Kavi Subhash to Beleghata) and Yellow (Noapara to the airport). That's 55 stations and about 73 km officially. The Orange Line's extension to Sector V is still in trial runs, so we left it out. We let the slime cross the Hooghly, because the Green Line already does. We left out the suburban trains to keep Kolkata metro-against-metro like Delhi and Bengaluru, but see the caveats. Pick the Kolkata tab in the live sim above.
| Measure | Slime mold | Kolkata Metro |
|---|---|---|
| Network length | 122 km | 66 km (straight lines) |
| People within 800 m of a line | 5.61 million (31%) | 5.13 million (28%) |
| People within 800 m, per km of line | 45,800 | 77,900 |
| Same length: people within 800 m | 3.54 million (73 km) | 5.13 million (66 km) |
| Share of its network within 1 km of the other's | 18% | 36% |
This is the slime's heaviest defeat. Trim it to roughly the metro's length (it still gets 11% more track) and it reaches 31% fewer people. Kolkata's 1984 Blue Line runs straight down the densest strip of the city, Dum Dum to Esplanade to Tollygunge, and almost every km of it has a crowd on both sides: 77,900 people per km, the most of any network in our league. The slime agrees about that spine, but then spends its length on long single arms: west across the river into Howrah and Domjur, north to Serampore, north-east to Barasat and south-west to Maheshtala. Those are the places the metro hasn't reached.
The biggest crowds more than 2 km from any open line, checked against the news. Unlike Delhi and Bengaluru, nothing is under construction for any of the top four: there are only plans and proposals.
| Hotspot (approx. centre) | People within 3 km | To nearest open line | Reality check |
|---|---|---|---|
| Maheshtala / Garden Reach–Metiabruz | 629,000 | 5.7 km | Proposal only The Purple Line's Kidderpore stop, the nearest one planned, was all but scrapped over land (Telegraph). A Maidan–Budge Budge metro via Maheshtala was only proposed in Sep 2026 (HT Bangla). |
| Inner Howrah (Belepole) | 620,000 | 2.1 km | Planned, not started Green Line extension Howrah Maidan–Santragachi, with a Belepole stop, is at the planning stage (India Hood). It's on the list of deferred lines that could restart (TOI). |
| Serampore (west bank) | 472,000 | 10.8 km | Talk only A Howrah–Hooghly metro (Serampore/Chandannagar) has been floated but not sanctioned (Statesman). The suburban main line serves it today. |
| Domjur / Andul, west of Santragachi | 195,000 | 10.1 km | Nothing beyond Santragachi The planned Green Line extension would stop about 3 km short. Suburban trains serve it today. |
Kolkata caveats. Station data is a Wikidata snapshot taken on 25 Oct 2026 (only stations marked "in use"), checked line by line against the news. Lines are drawn as straight links, so we measure 66 km against the official ~73 km. Leaving out the suburban trains matters most on the west bank: Serampore and Domjur have railway stations, so these are metro gaps, not rail deserts. We count residents only, so the Esplanade and Sector V office districts count for nothing. The Hooghly and the East Kolkata Wetlands aren't modelled as obstacles.
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