The second one actually had more of a 30's vibe. Heck, there was a boss fight with a giant firebreathing mechanical worm that works on gears, and some robot with six legs that was actually the tip of a zeppelin. That, and some planes had weird weapons like the twin tesla bolts. Seemed pretty steampunk to me.
Then again, these days newtonian punk and steampunk are pretty much considered the same. Alternate reality/history doesn't have anything to do with it, but usually its all about the art direction according to me. "Pop art", the 50s commercials/advertisements with a sort of dark humour (Incinerate plasmids being advertised like common soap), seems to be shared by a lot of steampunk games, along with a tendency to use pipes, steam, gears, copper, old technology turned new, weapons looking like they were homemade, etc...