Hi,
There is actually a way to implement the colonization campaign without Gates of Troy. But it is VERY tedious and not to mention, time-consuming. All you needed to do is to edit the text files in the campaign folder. Namely, sides.txt, armies.txt and cities.txt but making a back-up copy before doing this, of course. (I may have missed one or two more text files you'd have to edit) But if you're to edit the grand campaign and make it equivalent to the colonization campaign in Gates of Troy, it'll be nerve-wracking to do so!
And still, it may not be exactly the same because both Spartan and Gates of Troy have different ethnic groups and sets of units (I'm making a guess here as I DID take a look at Gates of Troy - I mean, GoT even have heroes! )
EDIT: Now I GOT GoT, I can see now that the colonisation campaign features the same ethnic groups/tribes as in Spartan's grand campaign, so it's extremely possible to make the same feature in Spartan.
