EcoFlip — Rules & Strategy
Reversi with an ecosystem bolted on, played on a 6×6 board. Ordinary Reversi rewards holding the most territory. This one punishes it — let a single species dominate the board and famine wipes it out. You have 20 seasons to keep all three species in balance.
The one-line version
The move that flips the most pieces is rarely the right move. You are not scored on how much you conquer — you are scored on how well you keep three species alive together.
Core rules
- Three-way rock-paper-scissors. 🐰 rabbits eat 🌱 grass, 🦊 foxes eat 🐰 rabbits, and 🌱 grass beats 🦊 foxes (a dead fox becomes fertilizer that feeds the grass). It's a closed loop — no species is unconditionally strongest.
- Habitat rule. You can't plant anywhere you like. A cell is only legal if at least one of its eight neighbors — orthogonal or diagonal — already holds life of any species. Unlike standard Reversi, you are not required to actually flip anything; the adjacency condition alone makes a cell playable.
- Sandwich flipping. Just like Reversi, an opposing species trapped between two of yours flips over. But only the species yours can actually prey on flips — rabbits only flip grass, foxes only flip rabbits, grass only flips foxes.
- Predation and overhunting. Flip the most abundant species in one move and you earn a predation bonus (3 points per cell flipped, capped at 15). Flip the rarest species instead and you take a penalty of the same size, in reverse. Every distinct neighboring species also adds +1 symbiosis (capped at +2).
- Overcrowding and famine. Once a species crosses 34% of the board, it gets an overcrowding warning. Still over the line next season, and famine strikes — the most densely packed individuals of that species starve first. Fallen cells become a corpse (💀), then fertile ground (🌾, +2 bonus) the season after. Winter — the final four-season act — tightens that cap to 30%.
- Extinction and revival. If a species' population hits zero, you're docked «remaining seasons × 2» points immediately — the earlier the extinction, the worse it hurts. Bring an extinct species back by planting it again and you earn +10.
- Seasons and harvest. The game runs 20 seasons across four acts of five seasons each. Every season banks a balance score, and every fifth season (5, 10, 15, 20) is a harvest — that season's balance score is multiplied ×3.
How the score actually works
At the end of each season the game takes the ratio of your smallest species count to your largest (a balance percentage, 0–100%) and awards 12 × balance² × (species alive / 3) points. Hit 75% balance or better with all three species alive and you build a harmony streak — worth up to +6 per season once the streak reaches three or more, and it resets the instant balance drops below 75% or a species disappears. The single hold slot (⇄) lets you bank your current piece for later, once per turn; leave anything sitting in hold when the 20 seasons run out and it costs you 5 points.
Your final stability score after season 20 sets the grade: S at 450+ · A at 360+ · B at 290+ (a passing run) · C at 180+ · anything below that is D. There are five badges to chase — Bloodless Seasons (zero extinctions), Domino (flip a chain of 6 or more cells in one move), Orchestra (hold a harmony streak of 3 or more), Reborn Forest (revive an extinct species and still finish B or better), and Legendary Warden (grade S).
Strategy
1. The move that flips the most is rarely the best move
Mass conversion scores you a predation bonus on the spot, but it also inflates the population of whichever species you're spreading — pushing it toward the 34% line faster than you'd expect. Check the three-species ratio before you flip; if you're already ahead in that species, skip the tempting big flip.
2. Flip the rarest species only when it's worth the penalty
Flipping the smallest population costs you points equal to the cells flipped — but if that species is one bad turn from extinction, eating the penalty to save a couple of its cells is cheaper than the extinction bleed that follows.
3. The overcrowding warning is a one-season reprieve
The moment the warning appears is your last chance to walk it back. Plant that species again this season and famine is locked in for the next. The safest response is to leave that species alone entirely until the warning clears.
4. Extinction is a bleed, not a one-time hit
The penalty scales as «remaining seasons × 2», so an early extinction is far more costly than a late one. Protect all three species hardest in the opening acts — losing one in the final season barely dents your score by comparison.
5. Rebalance right before the harvest lands
Harvest seasons (5, 10, 15, 20) triple whatever balance score you post that season. You can afford to drift out of balance in the four seasons leading up to it, but the move right before harvest should always restore it. Even a mid-game deficit can flip your final grade if you nail the balance on season 20.
6. Treat hold as an emergency valve, not storage
You only get one hold slot. Use it to park a piece you genuinely can't place well right now, then clear it on your very next turn. Carrying anything in hold into the closing seasons just eats a guaranteed 5-point penalty.
FAQ
Does the board change every day?
Yes. The daily forest is generated deterministically from the date (epoch #1 = 2026-08-16), so everyone playing on the same day sees the same forest. Free Play mode gives you a fresh random board any time you like.
How is my grade calculated?
Your final stability score after 20 seasons maps to a grade: S at 450+, A at 360+, B at 290+ (a passing run), C at 180+, and D below that. Playing at random usually lands you under C.
Do I need an account?
No. Nothing to install, nothing to sign up for. Open the page and you're playing.
Where is my progress stored?
Your best score, badges and daily progress live in your browser's local storage only — never sent to a server. A different device or a private window won't show your history.
When should I use hold (⇄)?
Once per turn you can swap your current piece into the single hold slot when there's nowhere good to plant it, or when the next piece matters more. Just make sure the hold slot is empty by the final seasons — anything left in it at game end costs you 5 points.
What's the difference between Daily and Free Play?
Daily (🌍) is a fixed forest determined by the date, so you're playing the exact same board as everyone else that day. Free Play (🎲) generates a new random forest each time and tracks its own separate best score.
Other guides
- Breath Snake — rules and strategy · a snake diving on a single breath, where depth pays but cargo weight makes the trip home expensive
- Cargo Snake — rules and strategy · a logistics snake where the crates you eat become body segments and only ship out tail-first
- Murder Grid — rules and strategy · solve a 6x6 sudoku for clues, catch two liars, name the culprit
- About playbuns · design principles, how the games are built, our advertising rules
This page is updated whenever the rules change. If you spot an error, tell us through contact.