Making some generative ASCII-art.

 | |     | | | |  o-O-o  o-O--o|O---o--O-||| |o--O-o |  |  |  | |       || |   
-O-| | o---O| | | | ||| | |||-O| | | | | | | || o---
| | | || | | |-O-o| | ||| |--O------o o--O-| || |
| | | |o-O----| | |o------O--o| | | o----O---o |O |
|---O---o | || | | |-O--o | |o-O---o | | | || |
| | |---OO--o| | | o----O----o-O-| | | | o----O------o| |
---o | | | |O-| | | | | | | | | | || | | |o-O---
o-O---o | o-O---o--O-| | | | o-O-| | | ||O--o o-O| |
| | | | | |-O--| | | | | o-O--o | |O--o-----O-----o|---------O--o
-| |---O-o-O-o | | | | o---O--o | | |O--o| | | o--O-----o | |o-O---

The Source

Jump head if it seems to you like some kind of foreign poetry.

Or you can try to read it anyway.

#!/usr/bin/env python3
from random import choice
import sys

w = 80
h = 40

if len(sys.argv) > 1:
depth = int(sys.argv[1])
else:
depth = 100

modular = True

x0 = w // 2
y0 = h // 2

start = "o"

# { node: { direction: [successor nodes]}}
rules = {
"|": {
"n": ["|", "|", "O"],
"s": ["|", "|", "O"],
},
"O": {
"w": ["-"],
"e": ["-"],
},
"-": {
"w": ["-", "-", "o"],
"e": ["-", "-", "o"],
},
"o": {
"n": ["|"],
"s": ["|"],
},
}


def display(world):
"Show the world"
print("\n".join("".join(row) for row in world))


def put(world, node, x, y):
"Position a node"
if modular:
x %= w
y %= h

world = world.copy()
if x in range(w) and y in range(h):
world[y][x] = node

return world


def move(x, y, d):
"Change x and y according to direction d"
if d == "n":
y -= 1
elif d == "s":
y += 1
elif d == "e":
x += 1
elif d == "w":
x -= 1
elif d == "ne":
x += 1
y -= 1
elif d == "nw":
x -= 1
y -= 1
elif d == "se":
x += 1
y += 1
elif d == "sw":
x -= 1
y += 1

return x, y


def possible_directions(node):
"Given a node return possible directions"
return list(rules[node].keys())


def possible_successors(node, d):
"Given a node and a direction return possible successors"
return rules[node][d]


def is_empty(world, x, y):
"Is a cell empty?"
if modular:
x %= w
y %= h

if x in range(w) and y in range(h):
return world[y][x] == " "
else:
return False


def is_valid_direction(world, d, x, y):
"Is the given direction valid?"
return is_empty(world, *move(x, y, d))


def grow(world, node, x, y, depth):
"Grow a node"
if depth:
directions = possible_directions(node)

# Filter valid directions
directions = [d for d in directions
if is_valid_direction(world, d, x, y)]

if directions:
for d in directions:
if is_valid_direction(world, d, x, y):
new_x, new_y = move(x, y, d)
new_node = choice(possible_successors(node, d))

world = put(world, new_node, new_x, new_y)
world = grow(world, new_node, new_x, new_y, depth-1)

return world


def main():
"Main function"
world = [[" "] * w for i in range(h)]

world = put(world, start, x0, y0)
world = grow(world, start, x0, y0, depth)

display(world)


if __name__ == "__main__":
main()

Outputs

With depth = 200:

--o-O| || |        | |O-o|  | |  | | o-O----|| |    | | |-O-o|-O-o    o-O-o--O-
|--O--o | | | || | | | | | | || | | | o-O-|| | ||| | |
| | | | o--O| o-O--o-O-| | |o-O------o | | |o---O-----o| | |
| | | | | | o------O| | | o---O--o | | o-O| | |o-O--|
-----O--| o----O---|-O-o | |O-----o | | | |-------O--oO----|| | o-
|| || | || | | | | | | | -O- | | |-O-o | || o--O--o |
|| |o-O--o-O-o---O-o | | | | | | -O- | | |-O-|--Oo--O--o | |
|o-O-|| | | | | | | | | o------O---o | o-O-o | | | | | | | |
o| | || o--O-o-O-o | | | | | | | | | | | | | | |O-o--O-O----
|| | |O-| || | | |-O-- | | | o---O----o || | | | | || | |
|| | | | || o-O---| | | | | o | | | || |-O-o o---O| | |
O--o | | ||----O--| o--------O-o | | | | | || | | | o-O| | o----
| |--O---o| |--O--o | O | | | | | | ||O-| | | | || | | |
| o----O--| | | o-O| | | | | o---O----o|||-----O---oo------O-o |
-O-| | | | | o---O-| | || | o-O--o | | |||O----o || ---O-o
| |-O-o | | |O--| |-O--oo---O-------|-O--- | ||o--O--|----O| | |
-o | | | | | || | | | || o-O----| | | ||| | | | | o-O
|-O-o | | | || o-O-o -O- | | |-O-o--O-o--O||| |--O-o | | |
--O-o| |O-|--O-----o-O| ||| | | | | | | | | || o--O-|-O----O--- | o
| || || | | || ||O---o--O-| | o---O--o-O--o o-O-| || | | | o-O-|

And 20:

                              |    -O-|                                        
| | |
o--O--o |
| | | |
| | | | |
| o--O-o-O--o
| | | | |
o------O--|-O-o
o--O|
| ||
-O- | o| |
| | || |
| | || o-O----
| | || | |
o----------O---------o
| | |
| o-O---o
| --O-- |
| | |
O | |