Add Achievement to Challenge (Runtime Based)
How to reach it
In Games & Emulation Main Screen's main list select a game, open the context menu (right click) and choose Add to Challenge (Total Runtime).
How it works
This dialog lets you add a runtime-based achievement for a previously selected game to a Challenge. This way you can also have games in challenges which are not supported by RetroAchievements.
Select a challenge with the Challenge dropdown. You can also add a challenge with the button.
Select a tier with the Tier dropdown. Add a tier with the button.
Define how long the game has to be played until the achievement is unlocked with the Total Runtime input fields.
For reference, you can view any previously added achievements for the selected challenge / tier in the lower table.