Fans of the "Portal" puzzle game series from Valve have been waiting for the release of the title's third installment. Reports say that Valve is planning to release "Portal 3" by the end of 2016 and fans have set their expectations from the upcoming installment.

"Portal" is a video puzzle game from Valve that involves solving passageways to enter and exit portals to advance the player's character in the game. It may sound easy, but there's also an antagonist in the game that hinders the character from advancing by locking the player's character inside a portal with no escape.

"Portal 2" ended up placing Chell, the protagonist, in a field with a companion cube. This mysterious end to the game left players with so many questions, and fans have been waiting for five years for answers in the release of "Portal 3."

There have been mentions that "Portal 3" will be launched by the end of 2016. Also, a site from the Valve Developer Community indicates that "Portal 3" is currently being developed. Valve has not confirmed nor released any statements yet regarding these two speculations.

With these, fans have found strong reasons to expect "Portal 3" soon in the market.

According to Digital Spy, Valve already filed for a trademark for "Portal 3" back in 2013 with the Trademarks and Design Registration Office of the European Union (OHIM). This was confirmed by the office and has kept fans of the game tuned in for more. Another thing that caught the fans' attention is the 2016 trailer of HTC Vive Pre that was launched in January. A woman in the trailer was seen wearing a similar outfit as Chell in the previous "Portal" games. In the HTC Vive compilation called "The Lab," a glimpse of "Portal" can be seen in a "Robot Repair" section. In this section, there is a demo where Atlas from "Portal 2" is being fixed, while leading to a "Portal" room that also has a companion cube.

Valve has not released any statements, but fans are speculating that the release of "Portal 3" happen at the end of the year.