Blue Portals is a unique Portal mod that has players traverse through new test chambers using only the single portal device and many new test elements.
Amazing new features, great designed chambers, balanced difficulty. 5th chamber is bad for me and in 7th chamber I got 'AI disabled' bug, but rest is almost perfect. The richest and the most original mod for Portal ever created. Also extended maps are good. Only jump pads and 'gravity gun' should have got better models.