The Talos Principle
40 Achievements
1,000
25-30h
Sigils Are Not Enough
Pick up a star.
20
36.75%
How to unlock the Sigils Are Not Enough achievement in The Talos Principle - Definitive Guide
Where you spawn into the hub, there's a bunch of towers with roman numerals in a circle around you. Activate the button on the tower marked "XX", then the button on the tower marked "VII". The water will drain and reveal a staircase down to the star.
There's another really easy one in A5 puzzle Friendly Crossfire that just requires the player to enter the smaller area on the right (which originally contained a mine) after completing it; then simply find the star there before leaving.
Pick a star any star will do! As you play, you will see them locked away, hidden from view and floating in crazy places. Some are much much easier to get than others and you don't always have to go out of your way to get one. The easiest one to get would be inside World A, level 3. Surrounding the spawn are pillars with roman numerals on them. There are switches in the middle of each pillar. Click VII(7) and then go click XX(20). The water will begin to drain and an opening will appear behind the spawn. Can't get any easier than hitting two buttons!
Click here for the guide on the rest of the main games 30 stars. Included is also the required amount of stars for the Gehenna storyline.