Shadowdark Finally Played Shadowdark

[Whizbang Dustyboots]

Probably not, but C&C reads a bit like TSR D&D but on a 3e d20 frame.

C&C also supports customization in the sense that you can probably just drop any 3E system on it and it'll be more or less fine.

 

[Whizbang Dustyboots]

I'm not in love with the SIEGE engine, but I've seen houserules that make it a little more straightforward.

Only the Troll Lords are in love with the SIEGE engine, and they seem determined to leave it as is forever.