For those trying to find a new Linux game that offers good graphics while not being a first person shooter with little to no plot -- as is the case for a majority of the commercial and open-source games available for Linux -- the Amnesia: The Dark Descent game is expected to be released next month. Amnesia: The Dark Descent is a graphic adventure horror game that will have a Linux-native client and has been in development by Frictional Games, the same studio that developed the Penumbra series.
For those curious about the game-play details for this horror game where the player has no access to actual weapons, see this posting on the web-site of Friction Games that describes their newest title at length. There's also a video they released, which is embedded below.
Amnesia: The Dark Descent uses the HPL Engine 2, which is an in-house 3D game engine of Frictional Games. HPL Engine 1 is what was used by the Penumbra series and its source-code was released as part of the Humble Indie Bundle deal. HPL Engine 2 builds upon this original engine and brings new features like coherent hierarchical culling as its dynamic culling system, shadow mapping support, screen-space ambient occlusion, and other enhancements to boost the OpenGL capabilities of this proprietary engine. Amnesia will be the first game to use this updated game engine.
In preparation for this game's release, which is currently set to premiere on the 8th of September, Frictional Games has released a graphics compatibility test application. This test application, which is available for Windows, Mac OS X, and 32-bit Linux (x86_64 support is coming soon), simply runs a few visual tests of the HPL Engine 2 to produce some screenshots. Frictional Games wants its fans and hopeful customers to run this test application on their system to hopefully spot any engine problems or graphics driver bugs prior to the game's official release.
Those interested in helping out or wanting to learn more, check out this forum thread.