Connect 4 with a twist

I'm (re)reading the Jeux et Strategie magazine and, in issue 28, I found this,

The translation: The game is played on a Go board. A border line represents the ground. The game is played on the intersections. The objective of the game is to align four stones in any direction. The constraint: starting from the second line, a stone can only be placed if the intersections directly below it, vertically, are occupied. The first move must therefore be made on the first line; the second move can be made either on the first line or on the intersection of the second line that is vertically aligned with the first stone, and so on.

At first I was hoping for a surprising little variant, but the rules, as I read them, just describes the classic Connect-4. Anyway, it made me think of a possible variant including captures: if the last placed piece has the effect of surrounding an enemy group, that group is captured, and all remaining pieces follow gravity. The player that makes the winning pattern wins (if both have a winning pattern, wins the player that just moved).

An example: 

a) Black (X) to move
b) Black plays at 1, forcing White's 2, then answer at 3
c) White plays at 1 making atari at Black's left group, but Black plays at 2 capturing White's group
d) The white pieces are removed, and the black pieces fall down, making a 4 in-a-row

. . . . . . . .      . . . . . . . .     . . . . . . . .     . . . . . . . .
. . . . . . . .      . . . . . . . .     . . . . . . . .     . . . . . . . .
. . o x . . . .      . . o x . . . .     . 1 o x . . . .     . . o x . . . .
. . x o x o . .      . 3 x o x o . .     2 x x o x o . .     . o x o x o . .
o . x o o o x .      o 2 x o o o x .     o o x o o o x .     x x x o o o x .
x . x o o x x .      x 1 x o o x x .     x x x o o x x .     x x x o o x x .
     (a)                  (b)                 (c)                 (d) 

I suspect that the game does not need a large space before either the game ends or captures become unavoidable. 

There are two modifications that I think are needed:

• The winning pattern must be a 5 in-a-row (4 in-a-row is too easy)
• The winning pattern must be exactly a 5 in-a-row (allowing for matches to develop more)
  

Choosing an appropriate number of columns and rows for this ruleset is left as an exercise for the reader!