Two updates in one day? For something as vital as checkpoints, yes. Here's what's been added in V1.2.1:
- Checkpoints (One when you clear level 3)
- New music track - Volcanic Depths (Listen to the beta version here)
- Fixed layering issues
- minor level changes
Give it a go here!
Sewage Escape DX (Scratch 3 version])can be found here.