Levees fail when overtopped for too long. Channels drain 2× faster. Pumps need dry grid to run. Watch the hydrograph — pre-position for the peak.
FLOODLINE
A flood engineering simulator
Physics you can trust. Decisions that count.
Based on real hydrology, historical floods, and SCS Type II methods.
FLOODLINE
A flood engineering simulator
Design & Engineering
Michael Flynn, PE Professional Engineer · Dam safety, hydrology, and hydraulic modeling
Hydrology grounded in real methods
SCS Type II rainfall distribution (NRCS TR-55)
SCS triangular unit hydrograph for upstream routing
HAZUS-MH-style stage-damage curves for buildings
100-year 24-hour rainfall depths from NOAA Atlas 14 (US) and approximate sources globally
Shallow-water cellular automaton with 8-neighbor gradient flux
Levee overtopping & piping-failure stress model
Stage-discharge rating curve at the tailwater boundary
Green-Ampt-like infiltration with antecedent moisture
Historical scenarios
Johnstown (1889) · Mississippi (1927) · Katrina (2005) · Cedar Rapids (2008) ·
Lumberton (2016) · Harvey (2017) · Oroville (2017) · Edenville (2020).
Storm profiles, terrain, and outcomes derived from real engineering and historical records.
Tech
Single-file HTML / Canvas 2D / Web Audio API. No external libraries, no images, no audio files.
All graphics and sound are procedurally generated at runtime.
Thanks
To the engineers maintaining NC's dam safety program, the hydrologists at ASDSO and USSD,
and the researchers whose work on post-Katrina levee forensics and post-Oroville spillway
investigation made each of those scenarios possible to model.
This is a simulation game, not an engineering tool. Do not use for design decisions.
Career Statistics
Floodline
A flood engineering simulator. Build levees, channels, and pumps against real hydrology. Levees breach under load. Infiltration matters. The hydrograph tells the truth — read it, and pre-position.
Free Play — Scenario Select
Historical scenarios use simplified but faithful parameters — river inflow, rainfall depth, breach risk, and terrain are derived from real events. This is a game, not an engineering tool.
Keys: 1–8 select tool · Space pause · [ / ] speed · R replay · Esc menu
Permanent Upgrades
Spend wallet money on perks that carry across every scenario. Purchases are permanent.
Wallet: $0
How to Play
Core loop
A storm is coming. Place levees, channels, pumps, and retention ponds to keep town damage below the threshold. Wallet money carries across scenarios; spend it on upgrades or let it fund bigger storms later.
Physics you can manipulate
Head gradient drives water — place levees to force detours; channels cut elevation and drain faster.
Tailwater backs up water when downstream discharge is high. Hospital may flood from the outlet, not from rain.
Antecedent moisture (AMC) — pre-wet soil infiltrates less. Historical events start with high AMC.
Breach — levees fail when overtopped; stress builds with head differential. Reinforce to raise threshold.
Soil type — sand drains fast, clay slow. Visible as subtle tint on grass cells.
Hotkeys
1–9 select tool · Space pause · [ / ] speed · Ctrl+Z undo H damage heatmap · C 1 m contours · P peak flood extent · V toggle iso / 2D Wheel zoom · Shift+Drag or middle-drag pan · Arrows nudge camera · 0 reset view R replay · M mute · ? this help · Esc menu
Campaign
Scenario Complete
About Floodline
Floodline is a California flood-defense simulation built on real water-system physics — levees, weirs, pump stations, and reservoir releases. Six historical scenarios span the 1986 Yuba flood to the 2017 Oroville spillway crisis. $2 indie release on itch.io and Steam.
How to play
Each scenario starts with an inflow forecast and current system state. Choose levee inspections, pump activation, gate operations, and (in some scenarios) controlled-flooding releases. Score points for protected area, lose for inundation. Real CA water hydrology.
Frequently asked questions
Is this based on real California floods?
Yes — the six scenarios reproduce real events: 1986 Yuba, 1997 New Year's, 2006 Sacramento, 2017 Oroville spillway, plus two synthetic ARkStorm scenarios from the USGS multi-hazard project.
How accurate is the hydrology?
First-order accurate for routing and storage; simplified for pump and gate response curves. Scenarios are calibrated against published post-event reports from DWR and USACE.
What's the hardest scenario?
2017 Oroville. Three independent failure modes (auxiliary spillway erosion, main spillway erosion, downstream evacuation logistics) all in 72 hours of game time.
Where can I buy it?
itch.io and Steam — search "Floodline". Single $2 purchase; free in-browser demo at boardgaminghub.com/Floodline.html.