To add further insight:
To reach an ending you sadly still have to read a bit. The post-mortem page will also give you enough instructions how to achieve each of them.
Ending 1 (easiest ending to achieve): score in your comment is 0
Ending 2 (you've completed bout half of the content): score is 1
Ending 3 (100% completion, reaching it is quite a chore): score is 3