I have been thinking about that sort of scenario. If your side (you or ally) has not destroyed an enemy unit or structure for a long time, or conquered a construction site, or constructed a unit/building, then you should probably get a warning that you'll be forced to retreat (similar to the warning that happens when you're mostly wiped off the map, but with more time available). The time before you get this warning could depend on the overall balance of the battle (as displayed with coloured graphics on top). Also, it seems reasonable to favour the defender. Perhaps double the amount of time the defender can go without accomplishing anything.
Maybe 25 seconds + (0 to 100%) of 35 seconds for attacker and an extra 25 seconds for defender. (Specific numbers separate from the gist of the idea. And I figure it would take more than a few tries to establish a model that didn't force the weaker part to adopt suboptimal tactics.)
I'd simply favour the defender and call it mutual retreat, but that would favour flying units hiding over water in the four corners or some such exploit.
Either that, or a stalemate mode that kicks in whenever population is 0 and recruits below X (50?) where similar requirements are made (build something, conquer something, destroy something) and time constraints are more severe. A more purposeful stalemate adjudication.
Or stalemate resolution could look primarily at the predominant terrain and see if any side is without suitable units (sea, land; air units being worthless for this purpose) - if either side has no presence in the primary terrain, a warning to that effect is displayed, with a timer for retreat/defeat.
Note for your case: Transports are not researched from the get-go, at least they were not when I played on the new campaign map.
Can you mount a force of warlocks and shamans? (Or just warlocks?) They traverse water, and warlocks can attack (but a significant shaman support would probably aid them greatly).
Last edited by Sinister; 24/07/13 08:45 PM.