This post is from Gaming on Nintendo: Portal is obviously a successful series, one that holds the distinction of being the first to make this writer actually upgrade the old computer to something newer that could run a recent title. Since we probably will never see an official release of Portal on Nintendo DS/3DS we can rest assured that the home coders have stepped up and completed, or at least are close, to doing just that.
Aperture Science DS takes the premise of Portal and implements it on Nintendo DS. Shooting portals in walls, floors and cielings then shooting another portal somewhere else is all included here. Additionally, this includes the level editor for gamers to create their own levels.
This is an initial public release and is not final. Think of this as more of a public beta, download it and have fun with it.