Tactics for the Swamp (Fortress).

In SoD, there's basically no one to fight with if you don't have Hydras. Hydras are definitely a must-have. Two Hydras are already a force, but six Griffins aren't. You can't upgrade Cows early. There's not enough Vassals. Lizards are useless without the Wistan. Experience shows that if you don't build them on day 1, you won't build them on day 2 either (either you don't need them, or you don't have the resources).

Tol, you probably haven't played SoD in a while ;) Hydras aren't built as often on day 1 as they are in TE. And if you don't have Hives and Nurseries, what's the point of having them anyway? They'll come to rush you on week 2, and you'll only have 2 Hydras in your army, the map isn't explored, and the paths aren't cleared. And all this is because of those two weak units that you built with your last resources, trading away all your resources, and that you won't even be able to buy on day 121 (there's no bank in SoD :D). If you have the money, I agree that you need to build them. But if, as described in the situation, you don't even have enough money for heroes, then Hydras will be an unjustified luxury :)
In general, you can't convey the situation in words to determine one or another development option. You need a save file, otherwise we're arguing about nothing :)