It's not a RIP! Only highly compressed - extracted size is over 1,4GB!

Portal is a single-player first-person action/puzzle video game
developed by Valve The game consists of a series of puzzles
which must be solved by teleporting the player's character and
other simple objects using a single handheld device, with the
goal of getting to an objective point. This "portal gun" and
the unusual physics it creates are the main selling point of
the game.

In Portal, players control Chell, a test participant in the
Aperture Science Enrichment Center. Gameplay revolves around
the "Aperture Science Handheld Portal Device"
(also known as the "portal gun"), a handheld device that can
create an intra-dimensional portal between flat planes,
allowing instant travel and a visual and physical connection
between any two different locations in 3D space. Portal ends
are restricted to planar surfaces, but if the portal ends
are on different planes, bizarre twists in geometry and
gravity can occur, such as the player walking into the
portal through a wall and "falling" up out of the floor
several feet behind where she started. An important aspect
is that objects retain their momentum as they pass through
the portals: an object that falls some distance before
entering a portal will continue moving at that same velocity
out of the other end. This allows the player to launch objects,
or even Chell, up to higher levels that lack appropriate
portal surfaces, among other possible effects. Only two
portal ends may be open at a time, one orange and one blue
in color. If a new portal end is created, it replaces the
previous portal of the same color. Either color may be used
as an entrance or exit portal. The portal gun is also used
to pick up objects in a similar manner to the gravity gun
from Half-Life 2, though it cannot 'punt' objects or drag
them from afar like the gravity gun can.