The main city level (Ol' Reliable) reminded me of playing Ratchet & Clank: Going Commando back in the day on the PS3. There were these Clank segments where you'd march around and blow apart dozens of Megacorp thugs in a city that had blue glowing windows and a familiar sort of vibe, good times.
You could probably throw in some helicopters in addition to the mecha come to think of it, though aiming might be tricky
If you could figure out a way to procedurally generate city levels and have some upgrades/power ups I think you could have a really polished arcade/endless mode, but I sense you plan on developing a full story and campaign. The dialogue takes a bit too long between pauses, it could be sped up to about twice the speed, maybe add a typewriting effect as well? I like that you're also hand painting the character portraits traditionally, that's a cool touch.
You could juice up the enemy combat a bit more by perhaps having them fizzle out or catch fire first and then explode? Or maybe leave behind broken wreckage to maybe loot or kick around? I know memory needs to be cleared so not all games can really handle having a million objects permanently in the level, but even some simple burn marks on the ground would be nice.
I appreciate also all the AGDG easter eggs, the Blorb plush on the dash is a fun touch!