Portal is a Source-engine puzzle game. Players use a first-person perspective to explore a three-dimensional environment that is broken up into a series of levels. The only device available to the player is a portal-placement gun that is used to solve the puzzles. Players can place up to two portals that can then transport the player (or anything else) through them.Portal is a puzzle-lite game with an emphasis on faster replays and conditional achievements.
Not surprisingly, it works at 5040 x 1050 as well. Quite a fun triple head game.
Note: I can't be certain of the origin of the error (whether it was my machine or the game) but the first time I tried loading @ 5040x1050 I kept receiving the "Failed to create D3D Device!" error that crashes some Valve games. This was solved for by adding "-dxlevel 81" to the launch config via right-clicking on the game in my Steam games list.
