You play as a human in a mech suit. The objective in Energize The Portals is exactly the title. You have to collect the energy cells, put them on the beacons and this will activate a nearby portal. When you enter the portal it will take you to the connected world. You must go back and forth between the worlds to get as high of a score as possible.

Now playable in web browser. I highly recommend you only use the web version as a last resort. It seems to be very buggy in some cases.