Every player should start with 2TCs from dark age, distributed in different position, then I believe the game will need more cooperation then before.
Case 2 v 2, player AB vs CD then the position of initial TC should be arranged in
AB AB
vs
CD CD
Case 3 v 3, player ABC vs DEF then the initial position should be
CA
AB BC
vs
DE EF
FD
Case 4 v 4, player ABCD vs EFGH, then the initial positions should be :
CD AB
AB CD
vs
EF GH
GH EF
Take 4v4 as an example:
(1) if left_AB was killed by left_EF + left_GH, player AB can still manage their cities in right AB
(2) right_A can support left_A to start the war on left hand side,
right_B can support left_B to start the war on left hand side,
left_C can support right_C to start the war on right hand side,
left_D can support right_D to start the war on right hand side.
so, every players are now on the edge as well as middle.