There's a bug in Deponia where the state for the puzzle game isn't properly restored leading to a softlock when a save is loaded.

To fix copy and paste the contents of fix.lua to the top of C:\Program Files (x86)\Steam\steamapps\common\Deponia\lua\voices_EN.lua

• Only tested on the Steam version (4.0.1386)
• Presumably if you run the game in a different language you would need to apply the same fix to the corresponding voices_XX.lua file
• There's a fan patch with other fixes here (although closed source as far as I can tell)