Tag: The Power of Paint, an independent puzzle game that inspired Portal 2, is now available for free on Steam. The first installment in Valve's mind-bending puzzle series was based on an indie game called Narbacular Drop, and the sequel's gel mechanics were similarly inspired by Tag. While projects like the new Portal Reloaded mod try to build a third entry in the franchise, gamers can now go back and play a prototype version of the second game.

Released in 2007, Portal became an instant pop-culture icon thanks to its innovative physics-based puzzles and charming story. The first game introduced players to GLaDOS, the Portal Gun and the world of Aperture Science, and in 2011 Portal 2 pushed the envelope once again. Putting a heavier focus on narrative through supporting characters like Wheatley and Cave Johnson, the sequel also brought in a host of new mechanics like anti-gravity beams, lasers and gels that can dramatically affect the environment. The Portal 2 Desolation mod and similar fan projects put their own spins on Valve's iconic series, though sadly an official Portal 3 has yet to be announced.

Related: First Footage of Valve's Cancelled Portal Prequel Game Emerges

As reported by PCGamesN, the Portal 2 prototype Tag: The Power of Paint is now available to play for free on Steam. The indie title from Tag Team gives players a gun loaded with red, green or blue paint. Players gain speed on red paint, bounce off green paint and stick to blue paint, allowing for many different environmental puzzles and acrobatic feats. Tag Team was hired by Valve to turn Tag's paint mechanic into Portal 2's gel mechanic, though the sticky blue paint was replaced by white paint that lets any surface hold a portal.

Portal 2 blue gel

While Tag: The Power of Paint is an entertaining game on its own, many fans are looking forward to Portal 3 instead. Recently a Valve writer addressed Portal 3, expressing that the developer should make a third entry in the series before he gets too old to work on it. Erik Wolpaw, who co-wrote the first two games in the Aperture Science saga, feels that fans should petition Valve president Game Newell to start work on a follow-up to Portal 2.

With a unique and innovative puzzle mechanic that allows for clever environmental brainteasers, Tag: The Power of Paint is a perfect title for any Portal fan to try. While the game directly inspired Portal 2, it still stands on its own thanks to the presence of the paint gun and blue sticky paint that were left out of Valve's project. While Portal 3 may not be coming soon, Portal 2 fans can now enjoy the historically relevant Tag: The Power of Paint for free.

Next: Valve Returns To Portal Universe In Free Steam Deck Demo Game

Sources: PCGamesN, Steam