Level

# Random level generation (140 characters)
# In a grid, start on the left edge and move up, down or right until you reach the right edge.
def l w,h;g=(1..h).map{[]};y=rand h;x=g[y][0]=0;(g[y][x]||=1;n=y+rand(-1..1);n>=0&&n<h&&g[n][x].nil?? y=n : x+=1)while x<w;g[y][x-1]=2;g;end

# Output:
irb(main):01:0> l(20,8).map{|r| puts r.map{|c| c || ' ' }.join(' ') }
                        1 1 1     1 1
  1 1                   1   1   1 1 1
  1 1             1 1 1 1   1 1 1   1
  1 1 1 1 1 1 1 1 1           1 1   1
0 1     1 1   1 1                   1 1
              1 1                     2
              1 1

=> [nil, nil, nil, nil, nil, nil, nil, nil]