They fell out of the game.
The pixlos were born inside Pixlo, a forgotten arcade cabinet at the back of a closed-down mall. For years they lived happily inside the screen.
The crash
One stormy night the machine crashed. The screen cracked, and twelve little pixlos tumbled out into the Hollow Woods: a real forest, with real cold, real hunger and a real dark.
The Glitch
Something crawled out with them. The Glitch is the error that crashed the game, and it's hungry for anything made of light. Pixlos are made of light.
The way home
The old arcade portal still flickers between the trees. It needs 12 days to charge. If anyone is still standing when it opens, they go home.
You
The pixlos can hear chat. They don't know why, but they listen. Every minute, you decide what they do next.