This will reset your achievements (located in Appdata\Roaming\Tess\config.dat).

Ran as-is, it will simply delete your config file. Unfortunately, you will lose any key settings doing this. If you want key settings:

1. Delete current config file
2. Enter game, set keys
3. Copy the config file, rename it to config.bak

The application will recognize and reproduce it to config.dat when ran.

Source: http://pastebin.com/3rd87feG