It looks like PORTAL, you play it the same way but it’s not PORTAL. This testing world is called Fling.
The core is the same like the legendary game. You have to move through testing chambers with one goal only – get to the next one. But some places are hard to reach and you may even get shot. Therefore you can use special gun that works similar to a hook. Grab on white places and pull up or forward. You certainly have to use your head to survive