"Interrupting" another player's turn

My fantasy strategy wargame Tyrant, includes an element just like you described. One option players have is to spend one action on their turn mixing potions and getting these "potion" cards. The advantage to potions is they can be played during anyone's turn and do not cost any actions to use. So the effect in the game is someone could be making a move and suddenly a different player could lay down a potion which creates a tornado and blows his army in another direction, or an explosive which blows up some of his troops, etc. The interesting effect this creates is all players with cards feel constantly involved in the game, even when it's not their turn to take actions. They feel like at any moment they have the potential to alter the gamescape or effect it in some way. This has been a longstanding flaw in wargames where players basic wander off waiting for their turn to come up, or while two players engage in a die rolling slugfest for 30 mintutes while others fall asleep. The answer to your basic question is that using a mechanic like the one you described creates a tighter sense of immersion in the game and helps players feel involved when it's not their turn.

I've been toying with the idea of turn interuption in a game that I have been working on. The game is a global level strategy wargame.

I think that this could be very cumbersome and painful for all involved in a larger game, especially as the complexity increases. An example of what I was thinking about.

Attacks can take place at any time during the game. The game consists of several Stages that make up one round. One of those Stages is the Move Stage (where all players take a turn moving their forces) which breaks down into a Move Phase (one player moves any or all of their forces to their allowable limit, one piece at a time). This Phase can be interrupted by any other player who perceives a serious threat developing - remember, attacking can be made at any time. At this point the player in Movement Phase must reduce their movement to the level of Steps. Confused?! So...we have..

Movement Stage : Movement Phase : Movement Step

An example: RED during his movement PHASE begins to move a navy towards position x on the board one hex at a time but continuously up to his movement allowance for that piece of let's say 20 hexes. After about 10 hexes of movement, BLUE does not like what he sees developing and wants to counter RED's movement. RED must now move one hex at a time (a movement STEP), and BLUE is allowed to also move any units one hex at a time. The players alternate until BLUE is satisfied that RED is not posing a threat.

It seems like a neat mechanic for immediately countering another players movement to thwart a possible attack, but is plagued with what I see as many many problems. Add another four players to this equation, plus the fact that players can attack at any time, plus that fact that BLUE may have already completed his movement phase, and thus moved many of his units to their movement allowance. It just becomes a big mess in my mind. The Move stage could last for ages.

I haven't playtested this idea, but bascially abandoned it right after I thought it up. Any comments would be appreciated.