Unit Limit / Save the Megagame

[Agrajag]

capnq said:

I can take a guess at that.

At minimum, you have to check every unit number up to the highest one assigned so far, even if thousands of lower numbered units have already been destroyed. Renumbering the units to account for casualties would be even more time consuming than just cycling through the range.

That's almost what I said - at most you have to check every unit number up to the highest one assigned so far, so there's no reason to go beyond that and reach all the way to the unit limit.
Furthermore, I don't think there could ever be any renumbering going on because IIRC the game intentionally keeps track of dead units.
But if it didn't, renumbering would actually be a piece of cake:
When unit dies:
1) Replace unit number between current one and last one.
2) "Kill" the dead unit that's now at the end.
And if renumbering is impossible due to engine constraints (for example, if a global spell remembers that it has been cast by unit #n and not the other way around), you could still reuse old numbers by merely making dead units "inactive" and whenever a new unit is created it can "steal" the dead unit's number.