I've been doing replacements, trying to make original, new gfx, based on the original sets from L1.  I have a few sets already complete: 0 - Dirt, 1 - Hell, 2 - Pastel, 3 - Pillar, and 7 - Snow.  If you would like to have my replacements, what's done so far is here: 

http://filebin.ca/tnkfru/L1.zip

Extract this .zip file directly into the bitmap folder.  

Here are all of the original L1 sets, if you'd like to help out: 0 - Dirt, 1 - Hell, 2 - Pastel, 3 - Pillar, 4 - Crystal, 5 - Brick, 6 - Rock, 7 - Snow, 8 - Bubble, and 9 - Xmas:

http://filebin.ca/cgbrpr/all_sets.zip

As I said above, 0, 1, 2, 3, and 7 are complete.  I am currently working on 4 - Crystal, creating an original idea Simon thought of.  So when i'm finished, it will be "4 - Gold Mine", instead of 4 - Crystal.   If you have any ideas or designs for the other sets, the only things recommended are:

1)you still include the same number in front, if the name is changed, so the set replaced is easily recognized, and

2)when you make your replacements, make your best attempt to use the original mask only (for those that don't know already, its the area inside the pink color).

It would be awesome to get help on this, since I just got lead on a new job, and may not have time to continue this soon.  Plus, the faster all 10 of these are replaced, the faster the game goes back up for download.  If you want to discuss any ideas you may have, or play L++, I'm in the IRC channel most of the time.

Thanks a lot, hope to see you there!