Hey guys!
I'm working on an Autosplitter for games in the Descent series, and have Descent 1 working for Rebirth 0.58.1. Here is the link:
https://www.dropbox.com/s/ozfo8bm9wnf2ili/Descent%20Rebirth%200.58.1.asl?dl=0
Also a note that this tracks the actual IGT as recorded by the game, in addition to RTA. Note that there's a "feature" in Descent where the IGT runs while you're in the exit tunnel, which you can hit escape to cancel, so IGT's still kind of bad.
I'm not yet sure how to get it to autosplit if you die in the mine. However, when I did a test run of the game, it split everything just fine from 1 to 27. Note it skips secret levels, counting them with the level you came from (so secret level 1 would be added to level 10's time).
I found that this does not like LiveSplit's SpeedRunsLive integration, and if you reload from saves it also resets the timer. Hmm, going to have to look into this more.