Phosphor is a visually impressive 3D first person shooter built in shockwave. The engine is as powerful as many standalone shooters, and is even comparable to the original unreal engine. Gameplay is precise and consistent, but is lacking in content.
The biggest problem with Phosphor is its limited player-base. Personally I have only ever seen one other player at a time. This is unfortunate, as the game is quite appealing, and would be great fun if you had a group of friends to play with.