Old concept trying too hard for novelty.
I can count off a few games that play far too similarly. That in itself wouldn't be fatal, because the formula you're using is a good one, and I can forgive you for going so far to be wackier than everyone before because the image of a baby covered in spiders is actually pretty awesome. Weapon upgrades are always a cool addition too, although very few weapons in your case break the formula of just having higher damage and rate of fire.
The walk speed is slow enough to -really- grind on me, though, and the jump function has screwed me a few times. Far as I can tell, if I hold left and briefly tap up, the game interprets it as double-tapping left and will throw me into a jump I didn't want. This just threw me straight down a boss' throat and I'm just not having enough fun to retry it.