Yes, but AI units a rarely idle.
Although, IMO the units appearent idling upon reaching their destination is an illusion: I've set AI units to move between X and Y and set an MU event sending the unit to Z to trigger on the turn that the unit reaches Y (i.e. calculating how long it takes the unit to get there and triggering on that turn). But when the unit reaches y and goes idle, it ignores the new MU event!
Even with MU event every turn, if the unit is adjacent to a unit not of that civ, the unit's orders are cleared. If the unit has any MPs remaining, the AI will give it new orders and you're screwed because an MU event every turn will have no effect in that situation as this is all taking place within the same turn.
In that example, you could use the UnitKilled trigger with MU to give the unit the same orders once it has destroyed the enemy unit but that's only if the rival unit's owner is at war. If the blocking rival unit's civ is at peace with the AI, then this solution is inapplicable.
A way to avoid that situation in a war scenario (i.e. a scen with only two civs--or with multiple civs but only warring civs have moveable units) is to keep any historical allies as one civ rather than seperate civs. That way if the AI is controlling one civ, it won't have its units' orders cleared by the units of other allied or peaceful civs.
But if the scenario comprises multiple civs with shifting alliances, then it gets more difficult because you may have enemy units and friendly units all moving around (and you know how the AI loves moving units about!) in the combat area.
[When designing such a scen, I would spawn one or two uber-AI units with attack role (e.g. Army) only when one of the AI's units is destroyed and set that attack unit to go to the attacker's capital. Obviously this wouldn't really work on a map where the civs are on seperate land masses.]
One system is to spawn AI units in the enemy city when it is captured by AI; capture of city triggers MU that gives orders to the AI units that have been attacking the city (their orders were cleared when adjacent to city's defenders). This would probably work best if using single AI Army units that will probably travel slowly and thus will all reach the city at about the same time.
Another way of forcing the AI to go to a specific part of the map without necessarily using MU is to reveal enemy units there by spawning an AI unit next to the enemy city you wish the AI to attack; it will either attack the units in the city or be attacked by them. Since the city defenders will probably not move from there (if the defender is also AI-controlled it will tend keep a garrison at least 3 units in a city and not move them) so the AI will send its units to the coordinates of the last revealed enemy unit (i.e. the enemy city).
[I'm assuming that this is the way I did it when I tested the above method.]
Note that the AI will always (at least that's been my experience) override if its city is undefended. It also overrides under various other circumstances that I can't remember now what they are.
What pisses me off is that the AI has this tendancy to wander the map EVEN WHEN AT WAR! So you'll get situations where instead of moving in the direction of the enemy, they'll just go off and explore the map.
This is Microprose's fault IMO; the wandering seems like its an AI 'canned strategy' meant to ensure that the AI will keep an eye on surrounding territory so that other civs don't settle there (note that the Civ1 AI did the same thing--and would follow you all over the bloody map to boot). Makes sense because AI doesn't do anything without something triggering it. The problem is that the AI only reacts (sends unit to coordinates of enemy unit) when an enemy unit has been revealed. When that unit is destroyed, the AI clears its orders. Here's where the bad the programming comes in: instead of being set to go towards the nearest enemy city, the AI will frequently start wandering again (i.e. units in enemy cities are not revealed so Ai does not go to the city). (That's why you get the effect of the unit going everywhere except where they're supposed to.)
If you have ToT, there is also another way around MU:
- Give all except heavy AI assault units (Armies) the 'override impassable' ability.
- Rename a terrain type to the same name (only ad a space at the end) as the primary terrain type used in the map.
- Set all other terrain types except the primary terrain to 'impassable.'
- Cover areas of the primary terrain type leading from the AI cities to the enemy cities (i.e. areas that you don't want the AI Armies to wander off to should their orders be cleared) with the edited terrain type.
The effect should be that when AI Army is created, it will only be able to travel from its home city to the enemy cities (i.e. will be forced to travel along a 'track').
You can always make the line of terrain some 3 squares wide so that the Armies can move around friendly units that enter track squares or so that they can attack enemy units that are not only directly in front of them (i.e. if the track is only 1 square wide then only enemy units can only be attacked if they enter the track infornt or behind the Army).
Others have tried somehitng like this in Civ3 (which also has the impassable feature) and it seems to work well, only the Civ3 doesn't wander when at war (the guys at Firaxis learnt something along the way
) thus it will go towards enemy cities anyway--the tracks just force it to go along a specific route, like bybassing other enemy cities and going straight for the capital or something.
