I've introduced, as temporary measures to give some time to transition, some degree of backwards compatibility:
- Levels using official VGASPECs - that is, the four from Orig-DOS, the five from Orig-Genesis, the one each from Covox and Prima, and "The Apple Computer Level" and "Sixes Not" - will be auto-converted at runtime to use the new system
- Levels using custom VGASPECs, in NeoLemmix format, will work via a very kludgy workaround. The solution to any bugs: Update to the new method of handling special graphics (ie: via graphic set mixing).
- Levels using custom VGASPECs, in DOS format, will not work. At all. Unless they're official ones, but that's only because they're autoconverted to use the new system and so the DOS VGASPEC file doesn't actually get used.
Note that in regards to the official sets, this doesn't mean the exact levels; any level that uses these official VGASPECs will work.
These backwards compatibility measures WILL eventually be removed, so switch over to the new system as soon as possible.