The Aperture Science Handheld Portal Device, or Portal Gun, is your most important tool. It allows you to create two interconnected portals: one blue, one orange. Anything that enters one portal will exit the other, preserving its momentum. This is the core mechanic of the game. You can only place portals on specific white surfaces. If you try to fire on a non-portal-friendly surface (like metal or glass), the portal will not appear. Experiment with placing portals on walls, floors, and ceilings. Remember, you can only have one blue and one orange portal active at a time; firing a new portal of the same color will replace the old one. Understanding momentum conservation through portals is key to solving advanced puzzles.
