Shortly before starting to hack SMB3, I got the urge to draw more 8-bit graphics. Thankfully, this urge struck close to C3, when I usually at least show some new graphics off. So far, I've drawn 8 of these retro-style sets.
I can see some Kirby's Adventure vibes mixed in too (like the sky and leaf backgrounds in the beach and forest tilesets, respectively). Overall the selections you've made work well with each other The underwater tileset with the light passing through is so lovely.
I can already see someone putting that ruins tileset to good use in a jungle or forest world. I like its versatility; one could get it to work around the idea of a temple's outdoors-like section, or maybe a forest-themed castle.
That sky set strikes me as "what if SMB 3 had Kirby's Adventure-esque artstyle", haha. Nice stuff.