Thanks so much! I haven't intentionally updated the dash mechanic, although there's every chance I've broken something elsewhere that's changed it (for context: this was my first ever coding project which I decided to dust off and finish for Finally Finish Something - the codebase is absolutely horrible, and changing anything breaks a mountain of completely unrelated things), but if it's working better I'm certainly not complaining!
The Y-sorting for the whole project is a bit all over the place, for future top-down projects I think I need to revise how I position sprites with regards to their origin as this seems to be the issue. I'll definitely be looking into this for the next one - it bothers me to no end too!
Rooms are made with a tilemap, with smaller tiles placed together to form larger ones - the tiles themselves are 16x16 pixels.
Thanks for all of your feedback through the jam and now, it's been incredibly helpful :)