my first attempt at pixel art

[v0id]

Recoloring tileset in general is also a bad idea

No it's not. Well it is, when used without brain enabled. But the technique in itself is valid where it makes sense.
Look e.g at Chrono Trigger whose tilesets used for the various eras are palette swaps.

[straelyn]

A few updated images. 1) whole level w/ collision tiles. 2) whole level w/o. 3) closeup showing some lava I rendered myself. I colorized the crystals by hand too, just for the hell of it.

[straelyn]

Here's the lava by itself. I'm so proud

[o11c]

The lava looks funny on the left and right edges, where the primary horizontal lines meet the vertical lines of the edge.

Your rooms are too square; are you familiar with automapping?

[Crush]

Unfortunately your lava doesn't tile well. When you try to build a larger lake, the tile borders immediately become visible:

[straelyn]

I'll see what I can do about some modifications. My main concern was that in order to get something to blend with tiling you need to give it a more generic look. On the other hand, who knows what I might accomplish with some creative blending. I'm saving the original somewhere at any rate; I think it looks cool

I haven't tried the automapping yet, but it sounds like a useful feature. I'll take a look at it.
Thanks a lot for the input everybody.

[straelyn]

Ok I developed a technique to help me keep track of all the edges. As you can see here it's starting to tile a lot better.

[mistergrey]

That is indeed looking better, but I do have one critique (which I hope you won't take personally) - While your lava does tile better the way you modified it, it is also very obvious where each tile is. For the most part, map tiles look best when you can't see the "grid" formed by the tiles. In this case, your lava tiles all have a dark border, which not only makes the grid very visible, but also makes the edges of each tile look deeper than the middle. My suggestions for this are:

1- Remove some of the darker color from the edges of your tiles, especially the ones you use in the center - it seems fine on the edge/border tiles to me. You can still have darker patches here and there for a more realistic look.
2- I'd probably toss in a tiny bit of some yellow shades, to give it more of that "magma" look. Only in small amounts anyway.
3- You might consider another "center" tile or two, that is darker all over - this could help give an appearance of depth, the closer to the middle it is.

That said... I really like how you've done the border tiles - the darker, curving lines look really good (in my opinion), particularly on the left and right sides.

[straelyn]

Here's an attempt to make the rooms look less square.

[straelyn]

Here's the "lava", only slightly more colorful, and it lines up at nearly any size.

[straelyn]

Here's some cool stuff I did that I thought I'd share, but it requires some explanation. I took the basic monster-skeleton.png, and learned that it dyes much better if I invert the color scheme first. So I took that inverted skeleton image and dyed it with tmw's dyecmd (using "W:#994040,772020,440808,000000"). Then, I made a sprite overlay for the eyes, ribs, fists, and leg-bones (which could probably be made dyable itself relatively easy). This is the awesomeness that ensued

edit: a few pixels were out of place