99% Boom support:

Missing: Bex support.
Doomguy bug (see bugs) cause incompatibilty with some maps.

Boom-Legacy: Legacy got it's own version of Booms "transfer heights" feature. Play around with it. Both got advantages/disadvantages.

3-D Objects:

Solid 3-D Floors, Opaque.
Solid Transparant 3-D Floors.
3-D water, Opaque.
3-D water, Translucent.
3-D Fog.
3-D Light.

Scripting:

Fraggle Script.
Possible to run consol commands in a script.

Other:

99% Dehacked support. - tell me if you come upon something that don't work with it.
Colored Sector Lighting.
New line Flag. Alltrigger - see tutorial 5.

If I've forgotten about anything it'll be added later. Like when you tell me about it.
It's supposed to be a long list of pin point features of each thing.. But I can't be arsed right now. It's to damn much work as of the moment.