Quick, 2-player, linear campaign system

If so, here's a quick first draft that you could explore and/or test:

where A, B and C are the respective "home spaces" of the three players (equivalent to the player's "own end" in the 2-player ryles), and "dc" is a disputed centre that brings the same benefits as the home space in terms of reinforcement for whomever player controls it right now (see below). The players' home spaces and the disputed centre are "grey" spaces; the rest are "clear" spaces. Terrain typology for all spaces should be agreed by all three players.

Players either take strategic bounds consecutively, always in the same clockwise or counter-clockwise order, or, if an element of unpredictability is desired, roll for order each round - with ties re-rolled until an unambiguous order is obtained for the three strategic bounds within that round.

Note that armies do not necessarily run into each other now, so it is possible to occupy and conquer a player's home space (or the disputed centre) without actually fighting a battle. I'd suggest having to spend two consecutive turns "pillaging" another player's grey space to conquer it without battle. Otherwise, it will be conquered if a battle is won there against the space's owner (or current controller, for the disputed centre).

Players can take the usual actions (and therefore will fight an enemy army if they move into the space they occupy, etc.), except that the rules for strategic initiative don't apply; the next strategic bound is always taken by the player who's next, irrespective of the action taken. A withdrawing army or an army retreating after losing a battle can only move into 1) a neighbouring unoccupied clear space or 2) a grey space, whether occupied or not, controlled by the withdrawing or retreating army; and never to the space from which the attacked army moved in. If more than one choice is available, it is picked by the moving army, unless it's executing a barely successful withdrawal, in which case the attacker will choose the destination. If the withdrawing or retreating army moves into an own-controlled grey space with an enemy army in it, a battle will immediately ensue. If an army that's been beaten in battle finds itself without a valid space to retreat into, the effect is the same as if its home space had been conquered.

If a player's home space is conquered by another player, either by battle or by pillaging (or if the army finds itself with no space to which it can retreat, see above), the conquered player's army is immediately taken to that home space if it's not already there, and the conquered player becomes a "tributary" of its conqueror. As long as the conquered player remains a tributary, their army cannot leave their home space, cannot reinforce, and will not fight their conqueror's army - so they can only intervene by defending their home space against the third player. While the player remains a tributary, the conquering suzerain can reinforce at the tributary's home space to receive an allied contingent of 3 elements taken from their current standing army - the suzerain can discard any excess element(s) of their own army in the process so that the combined army does not exceed 12 elements.

The tributary has the option of declaring independence again right after each battle that their suzerain loses against the third player, playing normally from that point on. If a tributary is attacked and defeated by the third player in the tributary's home space, they change suzerains, becoming a tributary of their new conqueror instead.

The "disputed centre" is initially neutral, and will become controlled by the first player to pillage it for two consecutive turns or winning a battle there. From that point on, control will be taken over by any player pillaging it for two consecutive turns or winning a battle against its current controller there. All players can move normally through it. If the current controller's army reinforces there, the space is treated as if it were its home space.

Other than the tributary/suzerain system, all diplomacy is non-binding and based only on mutual trust and goodwill.

A very rough draft just to give you some ideas to toy with; let me know what works and what fails.

Thanks!