If you have a new testing element to show off, this sort of striking theme might just ingrain it in the player's mind forever. As stated above, this theme is designed to leave an impact on the player so if you have simple yet innovative and unique puzzles, or those with brilliant moments of epiphany (colloquially known as 'aha' moments), use this theme. However, don't limit yourself to such simple tests. Tutorials - simple cube- and button-based testing and portalling/momentum puzzles.The official campaign uses the theme only for two things: On that note, however, do not confuse this with being dynamic the player must get the feeling that everything is dying, if not already dead, that this is the end, and that they are in solitude. This theme is supposed to give the effect that everything feels very organic. In the single-player campaign this was the first theme the player had encountered, and consequently had been designed to be visually striking and to leave as big an impact as possible on the player. Earlier tests in Portal 2 use this theme to make even a small test unforgettable.
