We’ve turned into a Hive, things are getting serious.

Good job for not using cheats. If it's an older version of the game, it should be a bit easier. I think the newer one is more difficult, although I don't know for sure, as I haven't played them, but I've heard about some hardcore version. Well, maybe you can try farming or just manage your finances better. I, for example, never hire the most expensive mercenaries, or maybe just one or two (Shadow and someone else), and even then, only later. I try to level up free units and take simpler specialists with the stats I need. I always take the Lynx, as a sniper, it's quite good, even if not the best.