Wow, lots of comments! I'll try to respond to everyone.
Do you have a place where I could see all the other 28 tilesets as pictures?
I do! A full list is available here:
http://untiedgames.com/assets/For the lava, to make it a bit smoother, the trick is to make several lava animations that all tile together and randomly use them.
I think the lava is very busy.
The random variation is a great idea. If I do a second version of this tileset, I'll try and make it smoother. I think I either need more frames, or less violent motion of the lava in order to smooth it out and reduce business.
Molten rock and molten metal are opaque. Plus, they're that colour because they're glowing, so even if they were translucent, the glow would still make them effectively opaque because it would drown out anything darker that's seen through them.
Yup, I'm aware of this! It was a stylistic choice to make the columns stand out through the lava. In the tileset I also include a version of the lava that is opaque, so people can use it any way they want. (And that WAS a very good description of lava!)
What Eishiya said regarding the lava being too bubbly. It looks like water. Maybe if it had fewer bubbles? Maybe if it 'peeled' open like lava does? Or, what if the lava moved in larger motions, since lava has very high viscosity?
In terms of peeling open, do you refer to the bubbles when they burst? I could try tweaking the animation to do this, it might make it a little less abrupt when they pop.
I think this look fantastic, overall! My only comment would be that I appreciate the highlight on the underside of the mid-ground pipe edges; and I'd love to see the same effect on the green platforms, considering they're so close to the lava.
I definitely agree with you there! Realistically, there should be a highlight on the bottom of those platforms. Usually I try to make the highlights in the terrain indicate where the player can stand and collide with the terrain, but I think I can figure something out to get a highlight on the underside without detracting from the appearance of collision.
Thank you for all the feedback!