I’d heard it as ZZT paid for Jill of the Jungle which let them afford Unreal’s longer development cycle while releasing other games (like Epic Pinball.) Epic Pinball and ZZT were two of my favorite games from the 90s.
The next game was Epic Pinball, and it was a huge hit. We estimate that it was the 3rd most successful shareware game ever created. Epic Pinball basically funded the startup of Digital Extremes as well as funding a lot of the development of Unreal.