Gold dots are food. The blue field behind them is the map's distance field: every empty square knows the direction of its nearest surviving pellet, drawn here as a stroke, and brightens as that pellet gets closer — so the basins you see are the paths a flea is being pointed along. Coloured dots are fleaz. Each one drags a short trail behind it that fades over about thirty ticks, so you can see the path it took. Classic VGA redraws the same data as the 1999 program did, in 6-pixel cells with hand-plotted arrows and no trails.

Each flea sees a 5×5 window — food, other fleaz, and the arrows underneath them — and picks one action per tick: sit, move in one of eight directions, attack, or eat. Every breathFreq ticks it respirates and spends one unit of food. At zero it starves. A tournament ends when the last flea dies.

Then the Midwife takes each species, kills the least fit half, pairs the survivors at random, and returns both parents plus two children. RANDOM never breeds — it is the control group, and the number to beat.