You can define required steps inside a learning path by checking the following option on the block.
Users won't be able to start the following steps of the learning path until they successfully passed the mandatory one.
The training will be considered as successful once all the mandatory steps are done and successful (ie. score higher than minimum score mentioned just below the "Mandatory" option, see above).
To calculate the average score of a training, Opigno will only consider the mandatory steps.