Paper IO revolves around a simple yet addictive concept: expanding your territory while preventing others from doing the same. Players control a small square that moves across the map, leaving a colored trail behind. By enclosing an area with the trail and returning to their base, players can claim that territory as their own. However, the game comes with an element of risk—if an opponent crosses a player’s trail before they complete an enclosure, they are eliminated instantly. This creates a dynamic environment where offense and defense are equally important.