Upcoming online game Gate has players create portals, here called "gates", to warp themselves to different areas in the game world. Hrm, that sounds familiar!
Portal, released in 2007 by U.S. developer Valve, has players solve puzzles by using the portal gun to open up teleports. Below is a screenshot from the game. 
According to website 4Gamer.net, Gate is a first-person shooter. However, it actually appears to be a third-person shooter. Gate, unlike Portal, does offer a variety in playable characters and weapons, but still.
The issue here isn't just portals — 2006's Prey had portals before Portal — but namely the color and the shape of them. What's more, in Gate players can make gates, portals, whatever á la Portal.
Last summer, another South Korean developer released PC title H.A.V.E. Online, a game that looked very much like Valve's Team Fortress.
Details about when Gate goes online in South Korea are forthcoming.
4Gamer.net - JC Entertainment，壁に"ゲート"を作ってワープしつつ戦う新作オンラインFPS「GATE」を韓国でサービス予定（GATE） [4Gamer]
