I'm working on a mod for XBlast:TNT called XBlast:Ultra,
so here's a few details that might interest you.

One of the major problems with XBlast is, in my opinion,
the lack of players, and the inability to play frequently
over Internet, due to the inability to locate games. People
have to make rendez-vous, which is not very convenient. In
consequence, the XBlast community is small and only popular
in universities and such. To fight against this, i'm going
to implement some chat functions, and automatic search of
games through Internet in XBlast:Ultra. It will also have
a built-in ladder system, similar to Blizzard's battle.net
to give you an idea.

I have ported the code for Win32 to MSVC++ 6 for the nice IDE
and debugger; in addition, i have removed all the GDI stuff
and replaced it by an OpenGL renderer. The bad news is,
a 3D hardware-accerated video card will be required, although
an old one should do the trick. I intend to use some OpenGL
features for special effects, like alpha-blending, zooms,
deformations, etc..

There will also be new extras, fog of war (rooms in which
you've never been are hidden), dark rooms (you need to get
candle extras to increase your viewing radius), scrollable
levels (more than one screen), and obviously bug fixes.

On the networking part, i planned to add a spectator mode,
and the ability to join a game at any time; a chat box for
in-game communication will be present too. I also wanted to
keep only a small part of the 500 levels (there's just too
many, and some are of a poor quality). They will be split
in 3 difficulty categories, so that newbies to the game
will get the "standard" levels first.

I will also drop support for multi-player on the same
screen, since it's supposed to be a pure Internet version.
This will simplify the interface, and make scrollable levels
easier to implement.

This new version will only be available for Win32, but
i might finish the port to X11 later if i have enough time
(and motivation!).