The syntax is straightforward:

completequest('quest_id_here')

Example:
To complete the very first main quest, "Lilac and Gooseberries" (ID: q101_lilac), you type:

completequest('q101_lilac')

Press Enter. The quest will immediately advance to “completed” status, grant any scripted rewards (XP, items), and trigger follow-up quests if the game’s logic allows.

If you want to test the endgame without playing 80 hours, complete main quests in sequence:
completequest('q101_lilac') → completequest('q201_velen') → completequest('q302_novigrad') → completequest('q401_skellige') etc.

⚠️ Warning: Completing main quests out of order can break your save beyond repair. Always keep a manual backup.

Completing quests with the console is not like using a “skip” button in a modern AAA game. The Witcher 3’s world state is held together by a web of facts (variables). Skipping blindly can: