As far this is concerned I got...
Tools available for nowaday systems:
- map planning, heights, placing objects/monsters/liquids/etc with Weland, instructions are the same of Forge (excluding visual mode)
- texturing and lights and activating tags with Vasara or Visual Mode plugins running under Aleph One
(Having the same map open either in A0 and in Weland is not possible, right? I get a quite verbose error from Weland if I try.) - terminals written in a simple text file using the same notation from the original manual
- change (basic) textures, weapons, objects and monsters bitmaps, sounds, phisics models with Shapefusion, using the same instructions from Anvil
- change (high resolution) textures, weapons, objects and monsters with plugins (but they must match the basic textures) written in MML (some familiarity with markup language might help)
- convert high-res textures in DDS format with Aorta or Gimp
- eventually, further behaviours changes using .lua (programming knowledge required)
- merge everything with Atque
- emulation: SheepShaver and/or Basilisk II. Then:
- Forge (version 1.0.4, beware of the limits if opening maps done with more than 1024 levels etc.)
- Anvil (version 1.0.3 to get around Shapefusion quirks in dealing with colour tables, 1.0.3b4 for auto-populate new frames features, but beware the bugs)
- Wail for sound editing
- Chisel for map effects
- Hackvil
By the way, I'm on Linux (Mint) but I'm not exactly what you call a power user, so at the moment I'm persevering in the heresy of having downloaded all the .exe files and threw them in Wine (they run!) I'll eventually try to get how to properly compile all the tools for my platform.
EDIT 3Aug2019: updated list