Realtime fluid sim is making lots of progress, though full 3D sims still appear to be computationally out of reach, at least for games that aren't focused exclusively on them. Here are some fun fluid sim examples from members of the Ten Minute Physics discord:
https://twitter.com/Michael_Moroz_/status/159507609967093350...
https://twitter.com/MytinoGames/status/1600278137564184579